UNIVERSITY  OF  CALIFORNIA   PUBLICATIONS 

COLLEGE  OF  AGRICULTURE 

AGRICULTURAL  EXPERIMENT  STATION 
BERKELEY,  CALIFORNIA 


A  STUDY  OF  SIDEDRAFT  AND 
TRACTOR  HITCHES 


BY 
ARTHUR  H.  HOFFMAN 


BULLETIN  No.  349 

October,  1922 


UNIVERSITY  OF  CALIFORNIA  PRESS 

BERKELEY,  CALIFORNIA 

1922 


David  P.  Barrows,  President  of  the  University. 


EXPERIMENT  STATION  STAFF 

HEADS  OF  DIVISIONS 

Thomas  Forsyth  Hunt,  Dean. 

Edward  J.  Wickson,  Horticulture  (Emeritus). 

,  Director  of  Resident  Instruction.     , 

C.  M.  Haring,  Veterinary  Science,  Director  of  Agricultural  Experiment  Station. 

B.  H.  Crocheron,  Director  of  Agricultural  Extension. 

C.  B.  Hutchison,  Plant  Breeding,  Director  of  the  Branch  of  the  College  of 

Agriculture  at  Davis. 
H.  J.  Webber,  Sub-tropical  Horticulture,  Director  of  Citrus  Experiment  Station. 
William  A.  Setchell,  Botany. 
Myer  E.  Jaffa,  Nutrition. 
Ralph  E.  Smith,  Plant  Pathology. 
John  W.  Gilmore,  Agronomy. 
Charles  F.  Shaw,  Soil  Technology. 
John  W.  Gregg,  Landscape  Gardening  and  Floriculture. 
Frederic  T.  Bioletti,  Viticulture  and  Fruit  Products. 
Warren  T.  Clarke,  Agricultural  Extension. 
Ernest  B.  Babcock,  Genetics. 
Gordon  H.  True,  Animal  Husbandry. 
Walter  Mulford,  Forestry. 
James  T.  Barrett,  Plant  Pathology. 
Fritz  W.  Woll,  Animal  Nutrition. 
W.  P.  Kelley,  Agricultural  Chemistry. 
H.  J.  Quayle,  Entomology. 
Elwood  Mead,  Rural  Institutions. 
H.  S.  Reed,  Plant  Physiology. 
L.  D.  Batchelor,  Orchard  Management. 
W.  L.  Howard,  Pomology. 
*Frank  Adams,  Irrigation  Investigations. 

C.  L.  Roadhouse,  Dairy  Industry. 
R.  L.  Adams,  Farm  Management. 

W.  B.  Herms,  Entomology  and  Parasitology. 
John  E.  Dougherty,  Poultry  Husbandry. 

D.  R.  Hoagland,  Plant  Nutrition. 
G.  H.  Hart,  Veterinary  Science. 

L.  J.  Fletcher,  Agricultural  Engineering. 
Edwin  C.  Voorhies,  Assistant  to  the  Dean. 


DIVISION  OF  AGRICULTURAL  ENGINEERING 

L.  J.  Fletcher  J.  Koeber 

A.  H.  Hoffman  E.  G.  McKibben 

B.  D.  Moses  J.  D.  Long 
R.  R.  Thomson  W.  L.  Zink 
H.  L.  Belton 


*  In  cooperation  with  Division  of  Agricultural  Engineering,  Bureau  of  Public  Roads,  U.  S. 
Department  of  Agriculture. 


A  STUDY  OF  SIDEDRAFT  AND  TRACTOR  HITCHES 


By  AETHUR  H.  HOFFMAN 


INTRODUCTION 

This  bulletin  has  been  prepared  mainly  to  enable  more  complete 
answer  to  numerous  requests  made  by  farmers  for  information  on 
various  phases  of  tractor  hitching. 


Fig.  l 

Sidedraft  is  the  sidewise  pull  on  the  rear  end  of  a  tractor  when  it 
draws  a  machine  that  does  not  trail  straight  behind. 


It  is  impossible  to  utilize  animal  or  mechanical  power  in  agricul- 
tural field  work  unless  it  be  applied  to  an  implement.  In  applying 
power  certain  mechanical  principles  govern.  These  have  long  been 
known  and  applied  by  engineers.  In  the  use  of  agricultural  machinery, 
however,  their  correct  application  has  often  been  lacking. 

*  For  valuable  assistance  received  in  the  preparation  of  this  work,  grateful 
acknowledgment  is  hereby  extended  to  L.  J.  Fletcher  and  others. 


114  UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 

Sidedraft. — Draft  means  pull  or  force.  Sidedraft  means  sidewise 
force  present  in  a  tractor  when  it  is  drawing  some  load  which  does  not 
trail  straight  back  from  the  center  of  pull  of  the  tractor,  but  pulls  off 
to  one  side,  as  does  the  chain  in  the  frontispiece  (Fig.  1).  (Sidedraft 
may  also  be  present  in  the  implement,  as  later  explained. )  This  means 
that  the  rear  end  of  the  tractor  is  pulled  bodily  to  the  side  against  the 
hubs  of  the  drive  wheels  (against  sprockets  in  track  type).  The 
drivers  in  turn  press  with  a  sidewise  force  against  the  soil  under  them. 
The  soil  resists  being  pushed  over  and,  if  firm  enough,  enables  the 
tractor  to  go  straight  forward.  Sometimes  the  side-force  is  so  great 
that  the  soil  is  pushed  over,  allowing  the  tractor  to  skid  to  one  side, 
one  driver  in  some  cases  dropping  into  the  furrow. 

Effects  of  sidedraft. — Sidedraft  causes  increased  friction,  especially 
on  the  tractor  wheel  bearings.  This  means  rapid  wear,  more  repairs, 
and  shorter  life  for  the  tractor.  It  makes  the  tractor  less  able  to  pull 
its  full  load  because  a  larger  part  of  the  power  developed  in  the 
engine  is  needed  just  to  move  the  tractor  itself.  This  means  more  fuel 
to  do  the  same  work  and  less  work  done  per  hour.  Sidedraft  makes 
the  tractor  harder  to  steer.  In  some  cases  it  is  found  absolutely  im- 
possible to  turn  the  tractor,  except  in  the  direction  of  the  sidedraft, 
without  first  removing  the  load  (lifting  out  plows,  for  example).  The 
result  is  crooked  furrows  and,  in  general,  poor,  uneven  work.  Side- 
draft  effects  are  practically  the  same  for  wheel  type  and  track  type 
tractors. 

Sidedraft  illustrated. — Sidedraft  is  present  in  a  tractor  whenever 
the  direction  of  the  pull  on  the  implement  is  not  parallel  to  the  direc- 
tion in  which  the  implement  is  moving  (considering  only  the  horizontal 
plane).  To  illustrate,  take  the  case  of  a  team  hitched  by  a  ten-foot 
chain  to  the  side  of  a  box  car  to  move  it  along  a  switchyard  track.  The 
horses  are  at  a  great  disadvantage  and  must  sidestep  in  order  to  keep 
pulling.  The  sidewise  pull  crowds  the  wheel  flanges  against  the  rail 
on  the  side  next  to  the  team,  greatly  increasing  friction.  If  the  team 
could  be  hitched  to  the  car  drawbar  head  and  could  walk  between  the 
rails  they  could  move  the  car  much  more  easily  and  comfortably. 
Similarly,  when  a  small  tractor  running  with  both  drivers  on  the 
unplowed  land  is  pulling  a  two  or  three  bottom  plow,  the  center  of 
resistance  in  the  plow  moves  in  a  line  considerably  offset  from  the  line 
in  which  the  drawbar  center  moves.  The  farther  from  the  furrow  wall 
the  tractor  runs,  the  greater  will  be  the  amount  of  offset.  Hence,  if 
an  inexperienced  plowman  in  order  to  make  his  plow  cut  full  width, 
drives  his  tractor  or  team  farther  over  on  the  land  instead  of  adjust- 
ing the  hitch  bars  on  his  plow,  he  is  increasing  sidedraft  unnecessarily. 


Bulletin  349] 


A   STUDY   OF   SIDEDRAFT   AND   TRACTOR    HITCHES 


115 


Not  only  is  the  tractor  affected,  but  the 
side  strains  and  wear  on  the  plow  are 
greatly  increased  as  a  result  of  such  mis- 
adjustment.  The  plow  will  also  pull  as 
much  as  20  per  cent  harder  in  some  cases 
and  the  work  done  will  not  be  so  good. 
When  sidedraft  is  unnecessary. — 
There  is  no  excuse  for  sidedraft  when  the 
load  is  such  that  it  can  just  as  well  trail 
straight  back  from  the  center  of  the 
drawbar ;  for  example,  in  most  scraping, 
leveling,  disking,  dragging,  packing, 
seeding,  cultivating,  hauling,  etc.    There 

Fig.    2 

More  sidedraft  than  necessary.  When  the 
tractor  is  run  farther  over  on  the  land  to  make 
'the  plow  take  full  cut,  sidedraft  is  unneces- 
sarily increased. 


need  be  no  sidedraft  in  any  of  these  cases  if  the  hitch  is  to  the  drawbar 
center.  Offsetting  the  hitch  on  the  tractor  drawbar  will  make  one 
driver  pull  more  of  the  load  than  is  carried  by  the  other,  but  will  not 
cause  sidedraft  in  the  implement  pulled,  provided  the  line  of  pull  is 
straight  forward ;  nor  on  the  tractor,  unless  the  load  is  so  great  that  the 
front  wheels  are  skidded 
to  one  side  by  the  un- 
equal loading  effects,  as 
later  explained. 


Fig.  3 

No  sidedraft  where  the 
tool  is  hitched  to  drawbar 
center  and  trails  straight 
back.  Examples:  scrapers 
and  levelers,  narrows,  culti- 
vators, rollers. 


Unavoidable  sidedraft. — Whenever  the  path  of  the  tractor  is  lim- 
ited, for  example,  by  the  edge  of  furrow  wall  or  of  standing  grain  or 
grass,  or  by  rows  of  trees  or  vines,  sidedraft  is  practically  unavoidable 
in  many  cases,  though,  as  will  be  shown  later,  it  may  be  reduced  so 
as  to  do  little  harm.    Binders  and  mowers  do  not  usually  produce  much 


116 


UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 


injurious  sidedraft  because  the  force  required  to  pull  them  is  relatively 
small.  When  the  center  lines  of  tractor  and  load  are  offset  and  the 
forces  needed  are  very  large,  as  in  plowing,  sidedraft  needs  to  be  looked 
after  very  carefully.  At  least  90  per  cent  of  sidedraft  troubles  occur 
in  plowing.  Small  tractors  able  to  pull  only  two  or  three  plow  bottoms 
have  more  difficulty  than  larger  outfits.  If  the  tractor  has  power 
enough  to  plow  out  its  own  width  or  more  at  the  required  depth,  the 

hitch  can  be  made  central,  the  pull 
straight  forward,  and  sidedraft 
thus  be  avoided. 

How  to  detect  sidedraft. — A 
rope,  chain,  hook,  loose  clevis,  or 
any  other  object  capable  of  trans- 
mitting a  pull,  will,  if  free  to  swivel 
at  both  ends,  set  itself  in  the  direc- 
tion of  the  force  it  is  transmitting. 
Hence,  if  there  is  somewhere  be- 
tween the  tractor  drawbar  and  the 
plow  a  link  or  clevis  free  to  turn  at 
both  ends,  its  position  when  the 
force  is  applied  will  show  the  direc- 
tion of  the  force.  Whenever  such  a 
free  link  is  not  parallel  to  the  direc- 
tion of  motion  but  makes  an  angle 
r§^       \\  %^S^$(fJ%P       with  it    (in  the  horizontal  plane), 

there  is  sidedraft.     See  clevises  in 


Fig.  4 

Test  for  sidedraft.  If  a  free  link  in 
the  hitch  (the  chain  of  Fig.  1 ;  the 
clevises,  Fig.  4)  makes  an  angle  with  the 
direction  of  motion,  there  is  sidedraft. 


figure  4  and  chain  in  figure  1.  Sometimes  there  is  in  the  hitch  no  link 
free  at  both  ends,  as  figure  5.  A  link  or  two  of  chain  or  a  clevis  may  be 
inserted  temporarily  and  by  its  direction  the  presence  or  absence  of 
sidedraft  be  shown.  This  test  applied  to  patented  hitches  said  to 
prevent  sidedraft  even  when  center  lines  of  tractor  and  of  plow  are 
offset  and  the  hitch  is  to  drawbar  center,  will  prove  the  truth  or  falsity 
of  such  claims. 

How  to  prevent  or  reduce  sidedraft. — A  study  of  the  underlying 
principles  shows  clearly  how  we  may  reduce  or  even  entirely  prevent 


Bulletin  349] 


A   STUDY   OF   SIDEDRAFT   AND   TRACTOR   HITCHES 


117 


sidedraft.    Assuming  a  rear  drive  four-wheel  tractor  and  the  hitch  to 
drawbar  center  unless  otherwise  specified : 

1.  Reduce  the  angle  of  offset  to  nothing,  and  there  iv'ill  be  no  side- 

draft. 

2.  Make  the  angle  of  offset  very  small,  and  the  sidedraft  will  be 

c o rrespon ding ly  s mall. 

3.  Reduce  the  total  draft  required,  and  the  sidedraft  will  be  reduced 

in  the  same  proportion. 
The  angle  of  offset  may  be  reduced  in  three  ways: 

a)  By  running  one  driver  in  the  furrow; 

b )  By  running  very  close  to  the  furrow ; 

c)  By  lengthening  the  hitch. 


Fig.  5 

No  free  link.  Sometimes,  as  here,  there  is  in  the  hitch  no  link 
free  at  both  ends.  A  link  or  two  of  chain  or  a  clevis  may  be 
inserted  to  make  the  test  for  sidedraft. 


If  we  run  one  driver  in  the  furrow,  as  in  figure  6,  and  adjust  the 
plow  hitch-bars  properly,  the  pull  on  the  plow  may  be  straight  forward 
or  even  slightly  toward  the  plowed  land,  which  is  some  advantage,  as 
later  explained.  Several  difficulties  are  encountered.  Unless  especially 
designed  for  such  use  the  tractor  will  be  badly  tilted  and  throw  its 
weight  against  the  wheel  bearings,  causing  excessive  friction  and  wear, 
possibly  even  worse  than  the  effects  of  sidedraft  which  we  are  trying 
to  avoid.  This  tilting  will  affect  the  oiling  system  in  some  tractors, 
and  cause  bearings  to  be  "  burned  out. ' '  Also  the  tilted  position  makes 
driving  a  rather  uncomfortable  job  for  the  operator.  At  least  two 
tractors  are  designed  for  such  running:  one,  the  Moline,  levels  up  by 
raising  the  drive  wheel  that  runs  on  the  land;  the  other,  the  Bean  (no 
longer  manufactured),  which  had  one  central  track- type  driver  and 
two  supporting  wheels,  leveled  up  by  lowering  one  supporting  wheel 


118 


UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 


into  the  furrow.  Another  objection  to  running  a  wheel  in  the  furrow 
is  that  under  certain  conditions  of  soil  and  kind  of  crop  the  resultant 
packing  of  the  subsoil  might  injure  the  crop. 

We  may  reduce  sidedraft  by  running  the  tractor  as  close  to  the 
furrow  mall  as  the  firmness  of  the  soil  will  permit  and  then  adjusting 
the  plow  hitch-bars  so  that  the  plow  will  just  take  full  width. 

We  may  lengthen  the  hitch. 
With  twenty  feet  of  chain  be- 
tween plow  and  tractor  the  angle 
of  offset  would  be  made  very 
small,  even  if  the  actual  offset  in 
inches  were  fairly  large.  Such 
an  arrangement  would  not  be 
practical  for  several  reasons, 
chief  among  them  being  the  very 
wide  headland  that  would  be 
needed  for  turning.  However, 
lengthening  a  hitch  by  one,  two, 
three,  or  even  four  feet  would  in 
many  cases  be  practicable  and 
would  greatly  reduce  the  injur- 
ious effects  of  sidedraft.      It  is 


Tig.  6 

Running  one  driver  in  the  furrow 

removes  left  sidedraft  from  the  plow 
and  may  even,  as  here,  cause  pull  to 
be  slightly  toward  the  plowed  land. 
This  makes  less  draft  by  reducing 
friction  between  landside  and  furrow 
wall.  Disadvantages  are  packing  of 
subsoil  and  troubles  due  to  tilting  of 
tractor. 


often  said  that  a  long  hitch  makes  a  machine  pull  harder.  Careful 
tests  show  that,  other  conditions  being  the  same,  this  is  not  the  case. 
A  long  series  of  tests  at  the  University  Farm,  Davis,  indicates  that 
when  the  pull  is  level  (that  is  to  say,  when  the  hitch  point  on  the 
object  pulled  is  at  the  same  height  above  ground  as  the  point  of 
attachment  on  the  drawbar  or  on  the  hame),  the  difference  between 
the  average  of  pulls  with  close  hitch  and  the  average  of  pulls  with 
fifty  feet  of  cable  between  is  less  than  one  per  cent. 

When,  however,  the  pull  is  not  level,  the  angle  that  the  hitch  makes 
with  the  horizontal  is  changed  when  the  length  of  hitch  is  changed. 


Bulletin  349] 


A   STUDY   OF   SIDEDRAFT   AND   TRACTOR   HITCHES 


119 


This  affects  the  draft  due  to  the 
fact  that  the  lifting  effect  on  the 
front  end  of  the  object  is  greater 
for  a  large  angle  of  trace  (hitch 
short  and  low  on  the  object) 
than  it  is  where  the  pull  is  level 
(angle  of  trace  equal  to  zero).  If 
the  hitch  point  on  the  object  is 
higher  than  the  point  of  attach- 
ment on  the  hame,  there  will  be  a 
downward  force  on  the  front  of 
the  object,  tending  to  press  it 
into  the  soil  and  so  to  increase 
draft. 


Fig.  7 

Sidedraft  reduced  by  running 
tractor  as  close  as  possible  to  furrow 
wall,  the  plow  hitch-bars  being  ad- 
justed to  take  just  full  cut. 


Fig.  8 

Sidedraft  further  reduced  by 
lengthening  the  hitch  by  three  feet  of 
chain  and  readjusting  plow  hitch-bars 
to  take  full  cut.  A  chain  hitch  does 
not  permit  of  backing  plow  to  clear 
out  accumulated  trash. 


Reducing  sidedraft  by  in- 
creasing effective  length  of  hitch. 
—The  effective  length  of  hitch 
between  tractor  and  implement 
may  be  increased  and  yet  the 
implement  be  kept  as  close  to  the 
tractor  as  before.  This  is  done 
by  attaching  a  chain  or  swinging 
drawbar  underneath  the  tractor 
ahead  of  the  regular  drawbar.  In 
this  way  the  angle  of  offset,  and 
hence  the  sidedraft,  is  reduced. 


120 


UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 


This  arrangement  also  helps  materially  in  turning  with  such  loads  as 
disks  and  cultivators.  (See  figs.  9  and  10).  In  making  such  an 
attachment  care  should  be  taken  that  the  parts  of  the  tractor  to  which 
attachment  is  made  are  strong  enough  to  bear  the  force  that  will  come 
upon  them  when  the  tractor  is  pulling. 


Fig.  9 

Sidedraft  reduced  by  lengthening  hitch  by  use  of  an  extra  draw- 
bar swinging  between  horizontal  guides  attached  (in  effect)  well 
forward  under  tractor.  If  pinned  rigidly  this  arrangement  increases 
sidedraft  effects  because  it  extends  a  rigid  drawbar  farther  behind 
the  rear  axle. 


Fig.  10 

Details  of  extra  swinging  drawbar.  Frame  bolted  to  regular 
drawbar  at  rear  and  carried  in  front  by  two  rods  attached  at 
either  side  to  tractor  crank  case. 


Reducing  the  total  draft  required  for  the  plow  will  reduce  side- 
draft  in  the  same  proportion.  We  may  do  this  by  having  the  shares 
sharp  and  the  friction  surfaces  of  share  and  moldboard  scouring  well, 
the  bearings  in  good  condition  and  well  lubricated,  and  all  parts  of 
the  plow  in  good  adjustment. 


Bulletin  349]         A  study  of  sidedraft  and  tractor  hitches         121 


Dividing  the  sidedraft  between  tractor  and  plow. — By  offsetting 
the  point  of  hitch  on  the  tractor  drawbar  we  may  take  off  of  the  plow 
much,  if  not  all,  of  the  sidedraft  due  to  the  pull  of  the  tractor.  This, 
however,  causes  the  load  to  be  heavier  on  the  driver  nearer  the  point 
of  hitch.  The  wheel  carrying  the  larger  load  will  slip  more  easily  than 
the  other.  Thus  we  see,  in  the  extreme  case,  the  more  lightly  loaded 
driver  tending  to  run  in  a  circle  around  the  more  heavily  loaded  one, 
shoving  over  the  front  of  the  tractor  toward  the  furrow.  This  means 
a  side  force  on  the  front  wheels.  Whenever  the  steering  wheels  must 
be  held  turned  toward  the  land  (fig.  11)  to  make  the  tractor  go  straight 
forward  there  will  be  strong  forces  pressing  the  axle  collars  against 
the  front  wheel  hubs.  More  power  is  therefore  needed  just  to  move 
the  tractor  and  less  left  to  do  the  plowing.  If  circumstances  compel 
us  to  have  the  center  lines  of 
tractor  and  plow  offset,  we  may 
divide  the  bad  effects  between 
tractor  and  plow  by  hitching 
slightly   (two  to  six  inches)   off 


Fig.  11 

Offsetting  the  hitch  makes  steer- 
ing harder.  When  steering  wheels 
must  be  held  at  a  considerable  angle 
to  make  the  tractor  go  straight  for- 
ward, wear  will  be  rapid  and  effici- 
ency low.  Sometimes,  as  here,  the 
whole  tractor  runs  askew,  due  to  poor 
hitch  arrangement. 


rJIfcv 


'ti&Bt'*- 


center  on  the  tractor  drawbar  and  adjusting  the  hitch  bars  of  the  plow 
so  that  the  pull  of  the  tractor  will  make  a  small  angle  with  the  direc- 
tion of  motion,  as  shown  in  figures  1  and  7.  As  explained  on  pages 
143-144,  "dividing  the  sidedraft"  may  balance  the  side  forces  on  the 
front  axles  in  the  case  of  certain  tractors,  thus  making  steering  easier. 

How  a  moldboard  plow  works. — A  moldboard  plow  is  a  sort  of 
double  wedge  which  in  being  pulled  forward  slides  between  the  furrow 
slice  and  the  furrow  wall  forcing  the  slice  over,  and  at  the  same  time 
slides  under  the  furrow  slice  forcing  it  up. 

Everyone  is  familiar  with  the  fact  that  we  cannot  successfully  move 
or  lift  a  heavy  object  unless  we  can  stand  on  something  solid,  some- 
thing able  to  resist  the  tendency  of  our  feet  to  move  in  the  opposite 
direction.  Likewise  we  find  it  much  easier  to  push  over  a  heavy  box 
if  we  have  a  solid  wall  against  which  to  brace  ourselves.  The  Avail 
gives  a  reaction  force  which  enables  us  to  push  on  the  box  and  still 
maintain  our  position.     In  the  same  way,  when  the  plow  wedge  is 


122  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 

pushed  in  between  furrow  slice  and  furrow  wall,  the  furrow  wall  must 
press  against  the  land-side  of  the  plow  with  a  force  equal  to  that 
needed  to  separate  the  slice  and  to  push  it  over  bodily,  say  fourteen 
inches.  If  the  land-side  hits  a  soft  spot  unable  to  give  the  required 
force,  the  partly  loosened  slice  will  push  the  plow  over  bodily  into  the 
soft  spot  and  the  furrow  will  not  be  straight.  It  is  common  experience 
that  it  is  very  hard  to  make  a  plow,  especially  a  single  bottom  one,  turn 
a  straight  furrow  in  making  the  last  round  to  finish  a  "land."  The 
reason  is  that  there  is  no  solid  soil  left  to  furnish  the  necessary  sidewise 
force  to  enable  the  plow  to  push  over  the  furrow  slice,  so  the  slice  itself 
pushes  the  plow  over.  It  is  like  a  man  in  a  light  row  boat  trying  to 
push  aside  a  heavy  floating  log ;  the  log  moves  scarcely  at  all ;  instead 
the  man  and  his  boat  move  back. 

Similarly  when  the  plow  wedge  slides  under  the  slice,  the  force 
needed  to  separate  the  slice  from  the  furrow  bottom  and  lift  it  cannot 
operate  unless  the  plow  has  a  firm  footing  on  which  to  stand.  That  is 
to  say,  the  furrow  bottom  must  resist  the  tendency  of  the  plow  to 
sink  down  into  it. 

In  the  old-fashioned  walking  plow  these  forces  supplied  by  furrow 
wall  and  furrow  bottom  cause  a  large  amount  of  friction  between  land- 
side  and  sole  and  the  earth.  In  modern  plows,  one  or  more  wheels  are 
used  to  supply  these  necessary  sidewise  and  upward  forces  and  to  sub- 
stitute the  lesser  friction  of  well-lubricated  wheel  bearings  for  the 
friction  between  iron  or  steel  and  earth. 

Side  force  always  present  in  plowing. — It  will  be  seen  from  the 
foregoing  that  sidewise  forces  and  upward  forces  are  always  and 
necessarily  present  in  the  use  of  a  moldboard  plow.  Plow  designers 
provide  for  these  side  forces  by  making  the  rjms  of  the  carrying  wheel 
of  "nonskid"  shape,  and  often  in  the  case  of  the  rear  wheel  (some- 
times the  front  furrow  wheel  also)  by  setting  it  to  run  at  an  angle  in 
the  corner  between  wall  and  bottom  of  the  furrow,  as  in  figure  1.  This 
placing  enables  the  wheels  to  supply  both  side  force  and  up  force  for 
moving  the  furrow  slice,  without  much  endwise  force  being  present  in 
the  bearings. 

It  is  possible,  though  perhaps  not  practical,  to  take  these  side  forces 
entirely  off  the  front  wheels  of  the  plow  and  supply  them  from  the 
pull  of  the  tractor  by  driving  the  tractor  with  one  wheel  in  the  furrow, 
as  in  figure  6,  or  even  on  the  plowed  ground,  and  adjusting  the  hitch- 
bars  of  the  plow  so  as  to  make  it  run  in  the  desired  direction.  The  pull 
would  then  be  obliquely  toward  the  plowed,  instead  of,  as  is  usual, 
toward  the  unplowed  land.  The  plow  would  then  run  lighter,  but  not 
enough  so  to  offset  the  great  disadvantage  of  running  one  driver  on  the 


BULLETIN   349]  A  STUDY   OF  SIDEDRAFT  AND   TRACTOR   HITCHES  123 

plowed  ground.  When  the  tractor  pulls  obliquely  toward  the  unplowed 
land,  the  front  wheels  of  the  plow  not  only  must  supply  their  part  of 
the  force  for  pushing  the  furrow  slice  sidewise,  but  must  in  addition 
bear  the  sidewise  part  of  the  tractor's  pull.  This  accounts  for  the 
before  mentioned  very  rapid  wear  in  the  wheel  bearings  of  plows  that 
occurs  when  the  pull  of  the  tractor  is  at  a  considerable  angle  with  the 
direction  of  motion. 

How  a  disk  plow  works. — In  general,  the  same  principles  of  force 
apply  to  both  disk  and  moldboard  type  plows.  The  disk  plow,  however, 
lifts  the  furrow  slice  somewhat  less  than  the  moldboard.  Hence  the 
upward  forces  and  downward  reactions  will  usually  be  slight  in  a  disk 
plow,  while  the  sidewise  forces  and  reactions  will  be  similar  to  those  of 
a  moldboard  plow  cutting  the  same  average  width  and  depth. 

Plow  adjustments. — Every  man  experienced  in  the  use  of  the  old- 
fashioned  walking  plow  knows  that  if  he  hitches  at  the  top  of  the 
vertical  adjustment  on  the  front  end  of  the  plow  beam,  the  plow  tends 
to  run  down  and  plow  deep.  Likewise,  by  lifting  up  on  the  plow 
handles  the  plowman  can  make  the  plow  run  still  deeper.  By  a  low 
hitch  and  by  putting  weight  on  the  plow  handles  one  can  make  the 
implement  plow  shallow  or  even  run  entirely  out  of  the  ground. 

Similarly,  by  hitching  toward  the  right  end  of  the  horizontal 
adjustment  at  the  front  end  of  the  beam,  the  plow  is  made  to  'Hake 
more  land"  (assuming  a  right-hand  plow)  ;  that  is  to  say,  to  travel 
in  a  line  offset  to  the  left;  and  by  hitching  to  the  left  end  the  offset 
is  increased  to  the  right,  thereby  making  it  take  less  land.  Each  plow 
in  a  gang  has  the  same  tendency  to  follow  its  hitch  that  it  would  have 
if  it  were  unbolted  from  its  place  in  the  gang  and  made  a  walking  plow 
without  any  wheels.  The  wheels  of  a  gang  plow,  together  with  the 
weight  of  the  plow  itself,  compel  a  given  depth  and  offset  almost 
regardless  of  the  height  and  angular  direction  of  the  pull  on  the  gang. 
It  is  therefore  a  relatively  easy  matter  to  make  the  mistake  of  hitching 
in  such  a  way  that  each  plow  is  forced  by  the  wheels  to  run  where  it 
does  not  want  to  go.  It  resists  as  much  as  it  can,  with  consequent 
harder  pulling  and  more  rapid  wear  on  the  bearings.  In  extreme  cases 
the  plows  will  tear  or  root  along  instead  of  cutting  cleanly  as  they 
should. 

In  some  cases  of  extremely  bad  adjustment  the  draft  may  be  lighter 
than  when  adjustment  is  correct,  because  the  work  done  may  be  much 
less.  Thus  in  figure  12  where  the  hitch  is  too  high  on  the  plow  so  that 
it  ' '  runs  on  its  nose, ' '  the  draft  was  found  to  be  353  pounds  less  than 
the  2071  pounds  required  for  the  same  plow  properly  adjusted.  The 
two  sets  of  eight  50-foot  test  runs  each  for  good  and  bad  adjustment 


124 


UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 


were  taken  in  the  same  field,  in  adjacent  rounds  of  the  gang  plow,  and 
the  pairs  of  individual  runs  in  both  sets  as  nearly  as  possible  side  by 
side. 

Careful  reading  and  following  of  directions  for  making  adjust- 
ments, to  be  found  in  the  manual  for  the  particular  plow,  will  pay  good 
dividends  in  saving  of  time  and  expense.  Nearly  all  the  implement 
manufacturers  publish  such  manuals.  The  buyer  should  insist  on 
getting  a  copy  with  the  implement  purchased. 

Adjusting  tractor  moldboard  plows  by  trial. — See  that  the  plows 
of  the  gang  are  properly  put  together;  that  all  beams  are  parallel; 
that  all  bolts  are  tight,  the  shares  sharp,  and  the  coulters  sharp  and 
properly  set. 


Fio-.  12 

Extremely  bad  adjustment  sometimes  makes  draft  lighter.  This 
may  be  due  to  the  fact  that  the  plow  may  be  taking  a  smaller  cut 
or  be  pulverizing  less  effectively.  Here,  too  high  a  hitch  runs  the 
plow  on  its  nose,  making  the  rear  bottom  cut  less  than  full  depth. 
The  draft  here  is  1718  lbs.  as  against  2071  lbs.  with  proper  adjustment. 


A  coulter  should  be  set  far  enough  to  landward  of  the  shin  to  give 
proper  clearance  between  the  plow  and  the  upper  part  of  the  furrow 
wall.  This  distance  varies  between  one-quarter  and  three-quarters  of 
an  inch,  depending  on  the  construction  of  the  plow  and  on  plowing 
conditions.  The  distance  forward  of  the  shin  that  the  coulter  should 
be  set  depends  in  part  on  the  nature  of  the  soil.  It  should  be  just  far 
enough  forward  that  the  furrow  slice  will  be  cut  cleanly  from  the 
furrow  wall,  with  no  tendency  for  it  to  break  or  tear  away  ahead  of  the 
Coulter.  This  holds  when  the  soil  is  moist  enough  to  plow  well.  In 
very  hard  and  dry  soil,  a  coulter  set  too  far  forward  will  tend  to  act  as 
a  depth  gauge  wheel  and  to  prevent  the  plow  from  going  down  to  the 
proper  depth.  A  rolling  coulter  should  never  be  set  close  enough  to 
rub  on  the  shin  of  the  plow.     If  there  is  much  trash  on  the  ground  a 


BULLETIN  349]  A  STUDY   OF  SIDEDRAFT  AND   TRACTOR   HITCHES 


125 


coulter  set  too  deep  will  push  it  forward  instead  of  cutting  it  cleanly. 
The  best  depth  depends  on  the  character  of  soil  and  trash,  and  can  be 
determined  only  by  trial. 

See  that  the  friction  surfaces  of  the  share,  moldboard,  and  land-side 
are  smooth  enough  to  scour  well,  and  that  there  is  sufficient  "  lead-to 
land,"  figure  13,  and  vertical  suction,  figure  14,  on  the  point  of  each 


Fig.  13 

"Lead  to  land"  or  horizontal  suction.  The  point  of  the  share 
should  curve  out  slightly  toward  the  unplowed  land  to  lessen  fric- 
tion. The  amount  varies  from  about  %  inch  to  %  inch  in  new 
shares.    It  is  measured  by  the  width  of  the  gap  at  x  in  this  figure. 


Fig.  14 

1  'Suck' '  or  vertical  suction.  This  keeps  the  plow  in  the  ground. 
It  should  be  %  inch  to  %  inch  in  a  new  share  measured  at  the 
widest  gap  (as  indicated)  when  the  plow  bottom  is  laid  on  a  level 
surface. 


share  of  the  gang.  Figures  15  and  16  show  a  steel  share  badly  worn 
and  ready  to  be  reforged.  It  is  good  economy  to  keep  an  extra  unworn 
share  to  be  used  by  the  blacksmith  as  a  model  to  enable  him  to  restore 
very  nearly  the  original  shape.  Without  such  a  guide  the  smith  will 
be  compelled  to  follow  his  own  ideas,  which  may  or  may  not  give 
good  results  when  the  share  gets  into  the  soil. 


126 


UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 


Hitch  to  center  of  tractor  drawbar  or  to  a  swinging  drawbar  free 
between  horizontal  guides.  By  means  of  levers  lower  the  plows  into 
the  soil  until  they  run  level  and  at  the  depth  desired,  with  the  hitch  on 
the  beam  about  halfway  up.  If  they  will  not  run  deep  enough  that 
way  or  if  there  is  not  weight  enough  on  the  power-lift  traction  wheel 


Fi 


15 


Ready  to  reforge  to  restore  shape.  Bottom  view  of  badly  worn 
share.  The  "lead-to-land"  is  all  gone  and  in  its  stead  there  is  a 
reverse  lead. 


Fig.  16 

Ready  to  reforge.  Landside  view  of  the  share  of  figure  15.  The 
vertical  suction  is  all  gone  and  instead  there  is  an  upward  trend  at 
the  bottom  of  the  point.  A  plow  with  such  a  share  is  very  hard  to 
keep  in  the  soil. 


to  prevent  its  slipping  when  used,  raise  the  hitch  little  by  little  on 
the  beam.  Lowering  the  hitch  at  the  tractor  will  have  much  the  same 
effect.  If  the  tractor  drawbar  is  higher  than  the  hitch  point  on  the 
plow  frame,  as  it  should  be,  lengthening  the  hitch  will  also  tend  to 
make  the  shares  run  deeper.  For  very  hard  soil  the  final  resort  is  to 
load  at  the  plow  beams  with  sacks  of  earth  or  other  weight  to  keep  the 
shares  in  at  the  required  depth.  See  that  the  plow  is  adjusted  to  run 
level,  so  that  it  cuts  the  same  depth  right  and  left  and  front  and  rear. 


BULLETIN   349]  A  STUDY   OF  SIDEDRAFT   AND  TRACTOR   HITCHES  127 

Driving  the  tractor  as  close  to  the  furrow  as  the  firmness  of  the  soil 
will  permit,  observe  whether  the  plow  takes  just  enough,  too  much,  or 
too  little  land.  If  too  little,  assuming  a  right-hand  plow,  shorten  the 
right  hitch-bar  or  lengthen  the  left  one ;  if  too  much,  do  the  opposite 
until  the  plow  just  cuts  out.  Some  hitch -bars  are  not  adjustable  as 
to  length,  but  may  be  adjusted  by  moving  sidewise  and  fastening  in 
different  holes  either  in  the  bar  or  on  the  front  end  of  the  plow-frame 
proper.  Next,  after  driving  the  tractor  a  short  distance,  apply  the 
"test  for  sidedraft"  (page  116).  If  there  is  a  considerable  angle  be- 
tween the  clevis  or  chain  and  the  direction  of  motion,  lengthen  the 
hitch,  if  feasible ;  otherwise  try  "dividing  the  sidedraft  between  tractor 
and  plow"  (page  143)  by  moving  the  point  of  hitch  on  the  tractor 
drawbar  over  one  hole  toward  the  furrow.  Be  sure  next  to  readjust 
the  plow  hitch-bars  to  take  more  land,  if  necessary,  in  order  to  enable 
the  tractor  to  run  close  to  the  furrow  wall. 

The  best  results  are  obtained  by  hitching  as  near  as  may  be  to 
drawbar  center,  running  tractor  as  close  as  possible  to  furrow  wall, 
hitching  as  low  as  we  can  on  plow  frame,  using  as  long  a  hitch  as  is 
practical. 

Adjusting  disk  plows. — The  instruction  manual  for  the  particular 
make  should  be  followed  closely. 

In  very  hard  ground  each  disk  of  a  disk  plow  tends  to  roll  out  of 
the  soil  and  run  along  like  a  wheel  on  top  of  the  ground.  This  is 
.especially  noticeable  when  the  disk  support  arms  are  set  so  that  the 
plane  of  the  disk  edge  is  too  nearly  parallel  to  the  direction  of  motion 
of  the  plow.  Setting  each  support  arm  or  bracket  so  that  the  disk 
is  somewhat  more  nearly  crosswise  of  the  direction  of  motion,  will 
make  it  dig  in  like  a  hoe. 

Up-  and  downdraft  on  plow  and  tractor. — How  may  we  transfer 
from  the  small  and  easily  overloaded  front-wheel  bearings  of  the  plow 
to  the  large  and  strong  driver  bearings  of  the  tractor  some  of  the  force 
needed  to  hold  up  the  front  end  of  the  plow  wedge  when  it  is  lifting 
the  furrow  slice ?  As  an  example  of  "how  not  to  do  it."  let  us  take  an 
old-fashioned  horse-drawn  walking  plow,  and  suppose  an  inexperienced 
plowman  has  hitched  as  high  as  possible  on  the  plow  beam  end,  yet  he 
wants  to  plow  shallow.  If  he  were  a  heavy  man  and  strong-armed,  he 
might,  possibly,  by  constantly  putting  his  weight  on  the  plow  handles, 
lift  the  front  end  of  the  beam  enough  to  plow  the  depth  he  wanted; 
but  he  would  be  a  marvel  of  strength  and  endurance  if  he  lasted  a  half- 
day  on  the  job.  Suppose  that  we  put  a  depth-gauge  wheel  on  the  same 
plow  and  hitch  to  a  tractor  by  a  short  chain  attached  as  high  as  possible 
on  the  plow  and  as  low  as  possible  on  the  tractor  and  set  the  depth 


128  UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 

wheel  to  plow  very  shallow,  as  figure  17.  In  this  arrangement  not  only 
does  the  pull  of  the  tractor  fail  to  furnish  any  of  the  upward  force 
needed  by  the  plow  wedge,  but  it  actually  pulls  downward  on  the  plow 
beam.  The  tractor  is  in  reality  resting  some  of  its  weight  on  the  depth 
wheel  of  the  plow.  The  depth  wheel  does  the  best  it  can  to  prevent  the 
plow  running  down  very  deep,  but  is  not  equal  to  the  task  and  is  pressed 
deeply  into  the  soil.  Its  bearings  wear  out  quickly  under  the  over- 
load and  the  pull  required  for  the  plow  may  be  increased  appreciably. 
At  the  same  time  we  have  by  taking  some  weight  off  the  tractor  drivers 
increased  their  tendency  to  slip.  If  we  hitch  as  shown  by  the  dotted 
line  in  the  same  figure,  we  take  the  down  force  off  the  depth  wheel  and 
put  it  on  the  drive  wheels  of  the  tractor  where  it  will  add  little  to  the 


Fig.  17 

* 

Tractor  "riding"  on  the  plow.  Tractor  pu'ls  downward  on  plow, 
pressing  depth  gauge  wheel  into  soil,  thereby  increasing  draft.  The 
hitch  shown  by  dotted  line  would  be  much  better. 

wear  of  the  large  bearings  and  where  it  may  be  needed  to  increase 
traction  by  preventing  slipping.  Of  course,  a  single  plow  would  pro- 
duce no  noticeable  effect  on  a  large  tractor ;  but  if  the  hitch  were  made 
in  a  similar  manner  to  a  gang  plow  having  about  as  many  bottoms  as 
the  tractor  could  pull,  taking  some  of  the  weight  off  the  drivers  would 
reduce  the  pulling  capacity. 

Very  often  one  sees,  as  in  figure  1,  plow  beams  loaded  down  with 
heavy  weights  to  keep  the  plow  at  the  required  depth  in  hard  soil. 
Usually  the  failure  to  plow  deeply  enough  is  due  to  share  points  worn 
so  badly  that  all  the  downward  "suction"  is  gone  (figures  14  and  16). 
A  better  remedy  than  loading  down  is  to  have  the  "suction"  restored 
by  reforging,  if  a  steel  share,  or  by  replacing  with  a  new  one  if  a  chilled 
cast  share  is  used.  Some  steel  shares  can  be  reshaped  by  hammering 
cold. 


Bulletin  349] 


A   STUDY   OF   SIDEDRAFT   AND   TRACTOR   HITCHES 


129 


Tongue  trucks  (fore  carriages)  are  generally  designed  to  relieve 
horses'  necks  of  excessive  weight  and  jerking.  When  the  machine  is 
to  be  drawn  by  a  tractor  it  is  usually  better  to  remove  the  truck  entirely 
and  connect  by  stub  pole  and  clevis.  When  used  as  shown,  figure  18, 
the  downward  pull  presses  the  truck  wheels  into  the  soil,  increasing 
draft  and  causing  rapid  wear.     When  the  truck  is  removed,  as  in 


lf^^% 


Fig.  18 

Tongue  trucks  are  designed  to  relieve  horses'  necks  of  weight 
and  jerking.  If  used  with  low  drawbar  tractor  the  pull  is  down- 
ward on  the  truck,  causing  heavy  draft  and  rapid  wear. 


Fig.  19 

Tongue  truck  removed.     The  extra  weight  on  the  rear  axles  of 
the  tractor  will  do  more  good  than  harm.     The  pull  will  be  lighter. 


figure  19,  the  extra  weight  rests  on  the  rear  wheels  of  the  tractor  where 
it  does  little  or  no  harm  and  may  do  good  by  increasing  traction.  If 
a  long  hitch  is  necessary  (for  example,  when  several  grain  drills  are 
drawn  by  the  same  tractor),  the  truck  may  be  needed.  The  longer 
hitch  lessens  the  downward  angle  and  hence  lessens  also  the  downward 
pull  on  the  truck.     In  some  machines  designed  for  tractor  operation, 


130 


UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 


for  instance,  the  leveler  shown  in  figure  20,  a  tongue  truck  is  used  to 
give  steadiness  of  pull  without  which  it  is  not  possible  to  get  satisfac- 
tory results,  especially  with  a  track-type  tractor  on  uneven  ground. 
The  truck  shown  is  too  high  for  the  drawbar  of  the  tractor  with  which 
it  is  here  used.  The  truck  wheels  are  pulled  clown  into  the  soil  increas- 
ing the  draft  unnecessarily. 

Length  of  hitch  affects  up-  and  downdraft. — If  the  tractor  draw- 
bar is  higher  than  the  level  of  hitch  on  the  plow  frame  proper, 
lengthening  the  hitch  will  decrease  the  lifting  effect  on  the  plow. 
Heuce,  if  we  lengthen  the  hitch  to  decrease  sidedraft  we  should  also 


Fig.  20 

Tongue  truck  designed  for  tractor  operation.  Having  A  long 
and  B  short  reduces  vertical  motion  of  tractor  drawbar  to  enable 
leveler  to  do  smooth  work  on  rough  ground.  The  pull  on  the  truck 
should  be  level,  or  slightly  up  instead  of  down. 


lower  the  hitch  on  the  plow  or  raise  it  on  the  tractor  if  we  wish  to 
plow  the  same  depth  as  before  and  avoid  excessive  downward  force 
on  the  plow  wheels. 

Center  of  resistance  and  true  line  of  draft  in  a  moldooard  plow. — 
When  a  single  bottom  general-purpose  type  walking  plow  is  turning  a 
furrow  slice  fourteen  inches  wide  and  seven  inches  deep  in  uniform 
soil,  the  center  of  resistance  is  at  a  point  (X,  fig.  21)  on  the  moldboard, 
about  three  inches  from  the  landside  surface,  about  three  inches  above 
the  bottom  level  and  about  fourteen  inches  back  from  the  share  point. 
For  other  widths  of  bottom  and  depths  of  cut,  the  center  of  resistance 
has  about  the  same  relative  position.  If  the  soil  has  a  tough  sod,  the 
center  of  resistance  will  be  relatively  higher;  if  we  are  turning  up  a 
hard  plow  pan,  it  will  be  relatively  lower.  Its  position  will  also  be 
influenced  slightly  by  the  shape  of  the  plow,  particularly  as  to  mold- 
board  and  share. 


BULLETIN   349]  A  STUDY  OF   SIDEDRAFT   AND   TRACTOR   HITCHES  131 

A  line  from  the  point  of  hitch  on  the  plow  beam  end  to  the  center 
of  resistance,  shows  the  actual  direction  of  the  pull  on  the  plow  before 
specified  when  it  is  working  freely.  This  is  the  line  of  draft.  The 
center  of  resistance  and  the  line  of  draft  may  be  located  by  pulling 
the  plow  at  its  proper  depth  using  a  short  piece  of  chain  to  attach 
it  to  the  tractor  drawbar  or  to  the  doubletree,  figures  22  and  22a.  By 
the  direction  it  takes  when  the  pull  is  on,  the  chain  will  point  backward 


Fig.  21 

The  center  of  resistance  in  a  14-inch  moldboard  plow  is  at  a 
point  x  on  the  moldboard,  about  3  inches  from  the  landside  surface, 
about  3  inches  above  the  bottom  level,  and  about  14  inches  back 
from  the  share  point.  It  varies  with  depth  of  plowing  and  with 
character  of  soil  (sod,  hardpan,  etc.). 


Fig.  22 

True  line  of  draft.  When  a  walking  plow  without  depth-gauge 
wheel  is  working  freely,  the  traces  drawing  it  take  the  direction  of 
the  true  line  of  draft  and  point  back  (along  line  shown  dotted)  to 
the  true  center  of  resistance. 


and  downward  to  the  true  center  of  resistance  along  the  true  line  of 
draft.  It  will  be  noted  that  practically  all  of  the  true  line  of  draft 
lies  below  the  plow  beam  and  not  parallel  to  the  straight  part  of  the 
beam.  If  the  plow  has  a  depth-gauge  wheel,  it  must  be  removed  or 
raised  off  the  ground  before  making  this  test. 

Wheeled  plows  cannot  be  tested  in  this  way  since  the  wheels  are 
designed  to  compel  the  plow  bottoms  to  move  parallel  to  their  land- 


132 


UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 


sides,  even  when  the  pull  of  the  tractor  is  oblique,  and  to  plow  at  a 
certain  depth,  even  though  a  high  hitch  on  the  beam  tends  to  make 
them  run  much  deeper.  For  such  plows  we  may  estimate  the  true 
line  of  draft  closely  enough  as  follows:  let  us  mark  on  the  middle  (one 
or)  two  moldboards  the  spots  we  estimate  as  their  centers  of  resistance ; 
then,  for  a  two-bottom  or  four-bottom  gang  the  common  center  of 
resistance  would  be  at  a  point  midway  between  the  two  marked  points ; 
for  a  three-bottom  or  a  five-bottom  gang  it  would  be  at  the  center  of 
resistance  of  the  middle  bottom.    To  get  in  the  wheeled  gang  plow  the 

point  corresponding  to  the  hitch  at  the 
front  end  of  the  beam  in  the  walking 
plow,  we  must  go  to  the  two  pins  (bolts, 
or  other  device)  by  which  the  plow 
proper  is  attached  to  the  plow  hitch-bars. 
The  point  sought  will  be  in  or  near  the 
line  through  the  two  pins  but  not  neces- 
sarily midway  between  them.  In  a  three- 
or  a  five-bottom  fourteen-inch  gang  it 
should  be  about  three  inches  to  the  right 
of  the  front  end  of  the  middle  plow 
beam ;  that  is  to  say,  it  is  almost  the 
same  as  that  of  the  middle  plow  of  the 
gang  if  it  were  detached  and  used  alone 

Fig.  22a 

True  line  of  draft.  Line-up  of  clevises 
shows  line  of  draft.  Dotted  line  points  back 
toward  center  of  resistance  of  moldboard  plow. 
The  horizontal  adjustment  position  used  will 
affect  position  of  the  line. 

as  a  walking  plow ;  in  two-  or  four-bottom  gangs  it  should  be  a  point 
three  inches  to  the  right  of  a  point  midway  between  the  front  ends  of 
the  middle  beams,  assuming  right-hand  plows.  Evidently  when  we 
adjust  the  point  of  hitch  up  and  down  and  sidewise  on  the  front  end  of 
the  gang  frame  to  get  the  depth  and  running  position  desired,  or  adjust 
the  lengths  of  the  ' '  A "  hitch  bars,  we  change  the  direction  of  the  line 
of  draft.  The  center  of  resistance  cannot  be  changed  much  in  a  given 
gang,  though  it  will  be  varied  some  by  depth  of  plowing  and  by  soil 
conditions  as  previously  stated.  The  point  of  hitch  on  the  tractor 
should  be  chosen  as  nearly  as  possible  in  the  same  straight  line  with 
the  line  of  draft  of  the  plow.  That  is  to  say,  the  most  satisfactory 
plow  hitch  is  that  in  which  the  tractor's  pull  is  as  nearly  as  may  be, 


BULLETIN  349]  A  STUDY   OF   SIDEDRAFT  AND  TRACTOR   HITCHES 


133 


not  only  parallel  to  but  also  in  the  same  straight  line  with  the  plow's 
true  line  of  draft  for  the  desired  depth.  Such  hitching  means  easier 
running,  less  wear,  and  better  work. 


MODEL    FOR    STUDYING    SIDEDRAFT    EFFECTS 

Sidedraft  effects  may  be  studied  and  illustrated  conveniently  by 
the  use  of  a  few  spring  balances  and  a  frame  representing  the  chassis 
of  a  tractor  as  shown  in  figure  23.  The  pull  on  balance  A  represents 
the  forward  pull  of  the  tractor,  that  on  B  represents  the  resistance  of 
the  implement  drawn,  that  on  C  is 
numerically  equal  to  the  sidedraft  and 
represents  the  resistance  of  the  soil 
enabling  the  rear  wheels  of  the  tractor  to 
go  straight  forward  in  spite  of  the  side- 
draft.  The  tension  on  C  is  adjusted 
until  the  frame  lines  up  parallel  to  A. 
In  the  figure,  vox  shows  the  position  of 
the  front  axle  and  yz  that  of  the  rear 
axle ;  uv  is  midway  between  front  and 
rear  axles  and  is  designed  for  attachment 
of  swinging  drawbars. 


•Fig.  23 

Model  for  studying  sidedraft  effects.  The 
frame,  wxzy,  represents  chassis  of  tractor,  A 
the  tractor's  pull,  B  the  implement's  resist- 
ance, C  the  sidedraft.  M  is  an  extra  rear- 
vvardly  extending  drawbar  which  may  be  at- 
tached. When  C  reads  zero  there  is  no  side- 
draft. 


The  figure  shows  the  simplest  case— that  of  a  tractor  having  its 
drawbar  in  line  with  the  rear  axle  and  the  point  of  attachment  at  the 
drawbar  center.  It  is  equivalent  to  the  draw-bar  shown  in  figure  23a. 
M  is  an  attachment  which  may  be  bolted  on  to  the  frame  to  represent 
the  common  case  of  tractors  having  drawbar  located  back  of  the  rear 
axle.  When  the  drawbar  to  which  attachment  is  made  is  either  for- 
ward of  or  to  rear  of  the  rear  axle,  or  when  hitch  is  not  to  drawbar 
center,  it  is  necessary  to  use  a  fourth  spring  balance  to  counteract  the 
sidewise  forces  on  the  front  axle. 

Whenever  balance  C  reads  zero,  sidedraft  is  absent  at  the  rear  axle. 


134 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 


DRAWBARS* 

True  point  of  hitch  on  a  tractor. — A  hitch  as  here  used  means  the 
connecting  member  between  tractor  and  implement  by  which  the  imple- 
ment is  pulled,  beginning  where  flexibility  begins  as  we  go  from  tractor 
toward  implement  and  ending  where  flexibility  ends  in  solid  attach- 
ment to  the  implement.  It  may  consist  of  a  bolt  or  pin,  a  clevis,  a 
rope,  cable,  chain,  or  set  of  chains,  a  straight  bar,  a  bent  bar,  or  any 
combination  of  the  foregoing. 

By  true  point  of  hitch  on  a  tractor  is  meant  that  point  on  the  end 
of  the  hitch  toward  the  tractor  where  freedom  of  motion  up,  down,  and 
sidewise  ceases  and  the  hitch  becomes  rigid  with  the  tractor  frame. 


Fig.  23a 

Drawbar  in  line  with  the  rear  axle.  Sidedraft,  if  any,  is  all 
carried  by  the  rear  wheels.  (Note:  This  tractor  is  no  longer 
manufactured.) 


The  position  of  this  true  point  of  hitch  is  a  matter  of  great  importance, 
especially  when  the  pull  is  heavy,  since  in  a  very  large  measure  it 
determines  how  the  tractor  will  act  under  given  circumstances.  To 
make  this  matter  clear  a  number  of  drawbar  arrangements  will  be 
shown  and  discussed. 

Illustrations :  Let  us  consider  first  a  hitch,  figure  24,  consisting  of 
a  heavy  steel  bar  having  an  eye  at  the  rear  end  and  a  ball  at  the  for- 
ward end,  the  ball  forming  part  of  a  tall-and-socket  joint  attached  to 
the  under  side  of  the  tractor  frame  somewhere  between  the  front  and 
rear  axles.  Let  us  suppose  that  there  are  no  guides  at  the  rear,  leaving 
the  hitch-bar  free  through  a  wide  range  to  swing  radially  from  the 


*  Several  years  ago  the  American  Society  of  Agricultural  Engineers  made  up 
a  list  of  recommended  specifications  for  tractor  drawbar  heights  and  offset  adjust- 
ments. Because  of  much  adverse  criticism,  however,  these  are  not  to  be  announced 
as  il standards  of  the  Society."     The  list  is  therefore  omitted  from  this  bulletin. 


Bulletin  349] 


A   STUDY   OF   SIDEDRAFT   AND   TRACTOR   HITCHES 


135 


ball  joint.  It  might  be  designated  as  a  radially  swinging  drawbar. 
The  true  point  of  hitch  in  this  case  would  be  the  center  of  the  ball-and- 
socket  joint.  Such,  a  drawbar  gives  the  hitch  freedom  to  take  its  best 
direction.  Being  long,  it  reduces  sidedraft  effects  when  the  implement 
runs  offset.    It  makes  steering  easier,  greatly  facilitating  turning  with 


Fig.  24 

Radially  swinging  drawbar.  A 
rigid  bar  pivoted  by  a  ball-and-socket 
joint  at  its  forward  end  and  having 
no  guide  of  any  kind  at  or  near  the 
rear  end.  If  the  ball-joint  is  placed 
far  forward  it  tends  to  increase  trac- 
tion in  track  type  tractors  by  holding 
down  the  front  end  of  the  tractor. 
This  is  valuable,  especially  on  the 
soft  soils  of  the  rice  fields. 


such  loads  as  disk  harrows,  pulverizers,  drags,  etc.  By  its  use  the  front 
ends  of  the  tracks  in  track-type  tractors  are  held  down,  giving  better 
contact,  hence  better  traction,  especially  on  soft  soils,  as  for,  example 
in  the  rice  fields.  If  the  location  of  the  ball  joint  is  central  between 
front  and  rear  axles,  sidedraft  effects,  if  any,  are  divided  equally 
between  front  and  rear  wheels.  This,  other  things  being  equal,  would 
tend  to  reduce  strains  in  the  frame.  Further,  as  in  every  case  where 
the  true  point  of  hitch  is  in  the  central  vertical  plane  lengthwise  of 
the  tractor,  the  draft  is  furnished  equally  by  both  drivers.  One  dis- 
advantage of  the  radially  swinging  drawbar  is  that  it  is  not  well 
adapted  for  backing. 


Fig.  25 

Pinning  a  drawbar.  If  the  radi- 
ally swinging  drawbar  of  figure  24  is 
bolted  to  the  tractor  as  in  figure  25, 
the  true  point  of  hitch  becomes  the 
eye  at  the  rear  end  of  the  drawbar. 
The  chief  advantages  of  the  swinging 
drawbar  are  lost  by  pinning. 


Figure  25  shows  the  same  drawbar  as  figure  24,  but  with  the  addi- 
tion of  a  stationary  guide-bar  to  which  the  swinging  drawbar  is  bolted. 
The  true  point  of  hitch  now  becomes  the  eye  at  the  extreme  rear  of 
the  drawbar.  It  is  no  longer  correct  to  call  it  a  swinging  drawbar.  A 
similar  case  is  shown  in  figure  26.  Such  an  arrangement  is  in  its 
effects  practically  the  same  as  if  we  had  hitched  to  a  hole  in  a  station- 
ary drawbar  the  same  distance  out  from  the  rear  axle  of  the  tractor. 


136 


UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 


Fig.  26 

Pinned  drawbar.  For  all  effects 
this  drawbar  is  the  same  as  a  station- 
ary drawbar  extending  out  the  same 
distance  from  the  rear  axle. 


Fig.  27 

Stationary  drawbar  extending 
back  of  the  rear  axle.  This  type  by 
its  lever  action  increases  the  sidedraft 
effects,  if  any,  on  the  rear  wheels. 


Fig.  28 

Drawbar  passing  over  rear  axle 

and  attaching  rigidly  to  forward  part 
of  frame.  Effects  are  the  same  as  for 
a  drawbar  consisting  of  the  frame 
itself  extended  back  the  same  distance. 
(Note:  This  drawbar  is  no  longer 
furnished    with    the   tractor   shown.) 


~T— 

|J1w-ffi5r/^     -^""*"*S!fl^ff    ' 

1       . 

1 

Fig.  29 

Drawbar  passing  under  rear  axle 

and  attaching  rigidly  to  forward  part 
of  frame.  If  pinned  in  one  of  the 
notches  shown,  it  becomes  in  effect  the 
same  as  a  stationary  drawbar  consist- 
ing of  the  frame  itself  extended  back 
the  same  distance. 


It  matters  not  at  all  so  far  as  draft  purposes  are  concerned,  pro- 
vided only  that  the  parts  are  made  strong  enough  to  withstand  the 
forces  they  are  to  transmit,  whether  a  stationary  drawbar  is  attached 
directly  to  the  rear  end  of  the  tractor  frame,  as  in  Figure  27,  or  goes 
over  the  rear  axle,  as  in  figure  28,  or  under  it,  as  in  figure  29,  and 
attaches  rigidly  to  a  forward  part  of  the  frame.  Going  from  tractor 
toward  implement  we  find  the  true  point  of  hitch  where  rigidity  ceases. 

If  a  drawbar  is  free  to  swing  between  horizontal  guides,  as  is  the 
upper  bar  in  figure  30,  it  has,  within  the  limits  set  by  the  guides,  all 
the  advantages  of  the  radially  swinging  drawbar  as  regards  sidedraft 
effects,  and  for  all  horizontal  effects  the  true  point  of  hitch  would  be 


Bulletin   349]  A  STUDY   OF  SIDEDRAFT   AND   TRACTOR   HITCHES  137 


Fig.  30 

Multiple  drawbar.  The  lower  draw- 
bar is  a  radially  swinging  drawbar 
within  the  limits  set  by  the  support- 
ing chain.  The  upper  drawbar  is 
swinging  between  horizontal  guides 
within  the  limits  set  by  the  stops, 
provided  it  is  not  pinned. 


Fig.  30a 

Multiple  drawbar.  A  stationary 
drawbar  and  a  drawbar  swinging 
between  horizontal  guides. 


Fig.  30& 

Multiple  drawbar.  A  stationary 
(loop)  drawbar  and  a  swinging  bar 
drawbar  supported  by  two  rods  and 
by  two  chains  of  adjustable  length. 


Fig.  31 

Adjustable  drawbar.  Adjustable 
vertically  and  swinging  between  hor- 
izontal guides  unless  pinned. 


the  front  end  of  the  bar.  But  for  up-and-down  effects  the  true  point 
of  hitch  is  the  rear  end  of  the  bar.  In  the  same  figure,  the  lower  bar 
has  the  true  point  of  hitch  at  the  front  end  for  both  horizontal  and 
vertical  effects  so  long  as  it  has  not  reached  the  limits  set  by  the  chain 
and  the  guides.  Beyond  those  limits,  the  rear  end  becomes  the  true 
point  of  hitch. 

In  figure  31  the  drawbar  is  equivalent  to  a  swinging  drawbar 
(unless  pinned)  for  horizontal  effects  and  to  a  stationary  but  adjust- 
able drawbar  for  vertical  effects. 

If  the  motion  of  a  swinging  drawbar  between  horizontal  guides  is 
limited  by  pins  set  in  the  guides  (a  very  common  arrangement),  the 


138 


UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 


Fig.  32 

Horizontally  adjustable  drawbar. 
The  lever  furnishes  a  quick  means  of 
adjusting  the  amount  of  offset.  By 
removing  the  connecting  bar  this 
drawbar  may  be  made  swinging  be- 
tween horizontal  guides. 


Fig.  33 

Adjustable  drawbar.  Vertical 
adjustability  is  secured  by  use  of  the 
turnbuckle,  and  horizontal  adjust- 
ability by  offsetting  to  the  several 
holes. 


front  end  of  the  bar  is  the  true  point  of  hitch  whenever  the  bar  does 
not  touch  the  pins.  Whenever  the  bar  is  against  a  pin,  the  rear  end 
of  the  bar  becomes  the  true  point  of  hitch. 

Thus  one  of  the  big  advantages  of  a  swinging  drawbar,  namely, 
reduction  of  sidedraft  by  lengthening  the  hitch,  may  be  lost  if  the 
drawbar  is  prevented  from  swinging.  A  drawbar  is  often  pinned 
during  the  turn  to  prevent  a  close-hitched  implement  from  getting  foul 
of  a  tractor  drive  wheel.    After  the  turn  the  pin  should  be  withdrawn. 

Especially  in  the  smaller  size  tractors  adjustability  of  the  true 
point  of  hitch  on  the  tractor  is  of  advantage  in  that  it  furnishes  a 
ready  means  of  adapting  the  tractor  to  implements  differing  widely  as 
to  the  height  of  hitch  they  require  and  the  amount  of  offset  at  which 
they  must  run.  It  may  also  aid  in  turning.  Many  different  devices 
are  used  to  obtain  adjustability.  Figures  31,  32,  and  33  show  a  few 
such  devices. 

The  curved  drawbar  with  or  without  a  roller  approaches  the  swing- 
ing drawbar  rather  closely  in  its  effects.  (See  figures  34  and  34a.) 
Within  the  limits  set  by  the  clamps,  the  drawbar  of  figure  34  is  equiva- 
lent to  a  swinging  drawbar  for  horizontal  effects  with  true  hitch  point, 
in  effect,  the  center  of  curvature  of  the  curved  drawbar.  For  vertical 
effects  it  is  swinging  also,  but  with  the  center  line  of  the  curved  bar 
itself  as  the  location  of  the  true  point  of  hitch. 


Bulletin  349 


A   STUDY   OF   SIDEDRAFT   AND   TRACTOR   HITCHES 


139 


Fig.  34 

Arc     and    roller    type    drawbar. 

Within  the  limits  set  by  the  clamps 
this  is  equivalent  for  horizontal  effects 
to  a  drawbar  swinging  between  hor- 
izontal guides.  For  vertical  effects  it 
is  equivalent  to  a  swinging  drawbar 
having  its  true  point  of  hitch  in  the 
center  line  of  the  curved  bar  itself. 


^gp 

mm 

— jr^l 

' ;"  i 

^^^HMBM^M^ 

*  V  ^ 

Fig  34a 

Curved  drawbar.  This  drawbar  is 
the  same  in  effect  as  that  of  figure 
34,  provided  the  attachment  on  the 
curved  bar  is  such  as  to  slide  along 
it  readily.  If  two  or  more  turns  of 
chain  are  taken  around  the  bar  it 
becomes  equivalent  to  a  stationary 
drawbar. 


True  point  of  hitch  on  the  implement. — Similarly,  the  true  point 
of  hitch  on  the  implement  should  be  considered.  As  in  the  case  of  the 
tractor  it  is  a  matter  of  where  rigidity  in  the  hitch  begins. 

In  a  hitch  consisting  only  of  a  chain  or  cable  it  will  evidently  be 
the  point  where  the  chain  or  cable  is  fastened  to  the  implement.  In 
a  rigid  plow  hitch,  "A,"  or  "elephant  ear"  type,  as  in  figure  35,  there 
may  be  two  such  true  points  of  hitch,  one,  the  center  of  the  bolt  at  X 
governing  for  horizontal  effects;  the  other,  in  the  center  line  of  the 
bolts  at  Y  governing  for  vertical  effects.  In  figure  35a  the  true  point  of 
hitch  for  horizontal  effects  is  in  the  part  of  the 
clevis  which  links  with  the  eye  at  the  forward 
end  of  the  hitch.  The  true  point  of  hitch  for 
vertical  effects  is  in  the  center  line  of  the  two 
bolts  by  which  the  hitch  is  hinged  to  the  plow 
proper. 


Fig.  35 

True  point  of  hitch  on  the  implement.  In  a  rigid 
plow  hitch  there  may  be  two  such  points,  one  at  x 
governing  for  horizontal  effects,  one  at  y  governing 
for  vertical  effects.  The  wooden  breakpin  at  z  acts 
as  a  safety  release. 


140 


UNIVERSITY  OF   CALIFORNIA — EXPERIMENT  STATION 


Fig.  35a 

True  point  of  hitch  on  the  imple- 
ment. Here  the  point  governing  for 
horizontal  effects  is  the  part  of  the 
clevis  that  links  with  the  eye  at  the 
forward  end  of  the  hitch,  x.  The 
point  governing  for  vertical  effects 
is  in  the  center  line  of  the  bolts  by 
which  plow  and  hitch  are  joined,  y. 
Wooden  breakpin  at  z. 

Model  for  studying  the  effects  of  offsetting  hitch. — A  few  spring 
balances  and  a  wooden  bar  may  enable  a  ready  study  of  the  effects 
produced  by  offsetting  the  hitch  on  the  tractor  drawbar.  The  bar  as 
used  in  figures  36,  37,  and  38  represents  the  drawbar  of  a  tractor  in 
the  simple  case  where  the  drawbar  is  at  the  position  of  the  rear  axle, 
as  in  figure  23a.  The  pulls  on  the  upper  two  spring  balances  represent 
the  individual  pulls  of  the  two  drive  wheels  of  the  tractor.  The  pull 
on  the  third  balance  represents  the  resistance  of  the  load  drawn.    In 


Fig.  36 

Model  for  studying  effects  of  off- 
setting hitch.  When  hitch  is  to  draw- 
bar center  traction  load  is  divided 
equally  between  the  two  drivers.  If 
there  is  no  sidedraft  this  holds  for 
all  cases  where  true  point  of  hitch 
is  central,  no  matter  how  far  for- 
ward or  back. 


Fig.  37 

Model  for  studying  effects  of  off- 
setting hitch.  When  hitch  is  at  a 
point  midway  between  drawbar 
center  and  middle  of  right  driver, 
the  right  driver  carries  three-fourths 
and  the  left  driver  one-fourth  of 
the  traction  load. 


Bulletin  349]  A  STUDY  OP  SIDEDRAFT  AND  TRACTOR  HITCHES  141 


figure  36  where  the  hitch  is  to  drawbar  center,  the  upper  two  balances 
read  ten  pounds  each,  the  lower  balance  reads  twenty ;  that  is,  the  two 
drivers  divide  the  traction  load  equally  between  them. 

In  figure  37,  where  the  hitch  is  halfway  between  drawbar  center 
and  middle  of  right  driver,  the  right  balance  reads  fifteen  pounds,  the 
left  one  five  pounds,  and  the  lower  one  twenty  pounds ;  that  is,  for  the 
offset  shown,  the  right  driver  carries 
three-fourths  and  the  left  driver  one- 
fourth  of  the  traction  load. 

In  figure  38,  where  the  hitch  is 
squarely  behind  the  right  driver,  the 
right  balance  reads  twenty  pounds;  the 
left  one  zero,  and  the  third  balance 
twenty  pounds;  that  is,  when  the  hitch 
is  squarely  behind  a  driver  that  driver 
carries  the  whole  traction  load.  The 
extra  offset  drawbar  hitch  shown  in 
figure  43  is  of  this  kind. 


Fig.  38 


Model  for  studying  effects  of  offsetting 
hitch.  When  hitch  is  squarely  behind  a  driver, 
that  driver  carries  the  whole  traction  load. 


Examples  of  sidedraft  and  unequal  loading  effects. — The  following 
sketches  and  solutions  are  given  as  concrete  illustrations  of  the  prin- 
ciples that  have  been  set  forth. 

Where,  as  in  figure  39,  the  true  point  of  hitch  on  the  plow  is  a  dis- 
tance "a"  behind  the  rear  axle  of  the  tractor  and  is  offset  a  distance 
"  b  "  from  the  center  line  of  the  tractor,  the  proportions  being  as  shown 
in  this  figure : 

1.  If  the  true  point  of  hitch  on  the  tractor  is  at  1,  midway  between 

front  and  rear  axles,  for  each  1000  pounds  pull  in  the  hitch 
member,  the  sidedraft  is  111  pounds,  divided  equally  between 
front  and  rear  wheels. 

2.  With  the  hitch  at  2,  a  distance  *4  L  forward  from  the  rear  axle, 

the  sidedraft  is  139  pounds,  one-quarter  carried  by  the  front 
wheels  and  three-quarters  by  the  rear  wheels. 

3.  With  the  hitch  at  3,  the  middle  of  the  rear  axle,  the  sidedraft  is 

187  pounds,  all  carried  by  the  rear  wheels. 


142  UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 

4.  With  the  hitch  at  4,  a  distance  *4  L  hack  of  the  rear  axle,  the 
sidedraft  is  259  pounds  at  the  drawbar.  This  is  increased 
by  the  lever  action  of  the  rearwardly  extending  drawbar  to 
324  pounds  at  the  rear  axle.  The  same  lever  action  puts  a 
side  force  of  65  pounds  to  the  left  on  the  front  axle.  (Offset 
angle  here  is  15°.) 


Fig.  39 
How  the  position  of  the  true  point  of  hitch  on  the  tractor  affects  sidedraft. 


Fig.  40 
How  putting  the  plow  farther  back  affects  sidedraft. 

Where,  as  in  figure  40,  the  distance  "2a"  back  from  the  rear  axle 
is  double  that  of  figure  39,  the  offset  distance  "b"  remaining  the  same 
as  before : 

1.  With  the  true  point  of  hitch  on  the  tractor  at  1,  for  each  1000 

pounds  pull  in  the  hitch  member  the  sidedraft  is  70  pounds, 
divided  equally  between  front  and  rear  wheels. 

2.  With  hitch  at  2,  the  sidedraft  is  80  pounds,  borne  one-quarter 

by  front  and  three-quarters  by  rear  wheels. 

3.  With  the  hitch  at  3,  the  sidedraft  is  95  pounds,  all  borne  by  the 

rear  wheels. 


BULLETIN  349]  A  STUDY   OF  SIDEDRAFT  AND  TRACTOR   HITCHES  143 

4.  With  the  hitch  at  4,  the  sidedraft  is  114  pounds  at  the  drawbar, 
143  pounds  at  the  rear  axle  and  29  pounds  to  the  left  at  the 
front  axle. 

With  the  hitch,  as  in  figure  41,  at  4  on  the  tractor  and  along  x  to 
the  plow,  the  offset  distance  being  "&"  (making  the  offset  angle  15°), 


Fig.  41 
How  the  amount  of  offset  distance  affects  sidedraft. 

the  sidedraft  will  be  259  pounds  at  the  drawbar  (as  in  case  4  of  figure 
39)  for  each  1000  pounds  pull  in  the  hitch  member.  If  now  the  adjust- 
ment of  the  hitch  on  the  plow  be  changed  so  that  the  plow  leads  off  to 
the  right,  making  the  hitch  member  take  the  position  y,  offset  distance 

V  (offset  angle  30°),  the  sidedraft  will  be  -   X  1000,  or  500  pounds 

c 

for  each  1000  pounds  pull  in  the  hitch  member. 

For  any  offset  distance  "5"  and  true  length  of  hitch  "c"  (i.e.,  the 

distance  between  the  true  points  of  hitch  on  plow  and  on  tractor  with 

reference  to  horizontal  effects),  the  sidedraft  at  the  point  of  hitch  on 

the  tractor  will  be  the  fraction  -  of  the  pull  in  the  hitch  member. 

c  ^ 

In  figure  42,  with  the  values  of  "a"  and  "&"  as  in  figures  39 

and  41 : 

4.  With  the  hitch  point  at  4  the  sidedraft  at  the  drawbar  will  be 

259  pounds  for  each  1000  pounds  in  the  hitch  member.  The 
side  force  on  the  front  wheels  is  toward  the  left. 

5.  With  the  hitch  point  at  5,  the  side  draft  at  the  drawbar  will  be 

zero,  but  the  right  driver  will  carry  684  of  each  1000  pounds 
and  the  left  driver  316  pounds.  On  a  heavy  pull,  this  tends 
to  make  the  right  driver  slip  more  and  the  left  one  tend  to 
run  ahead  in  a  circle  with  the  right  driver  as  a  center,  thus 
putting  a  side  force  toward  the  right  on  the  front  wheels. 


144 


UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 


With  the  hitch  point  at  6,  halfway  between  4  and  5,  the  side- 
draft  at  the  drawbar  will  be  130  pounds  for  each  1000  pounds 
pull.  The  offset  of  distance  y2  "6"  on  the  drawbar  will 
cause  the  right  driver  to  carry  592  pounds  and  the  left  408 


Fig.  42 
"Dividing  the  sidedraft  between  tractor  and  plow." 

pounds  of  each  1000  pounds  of  the  forward  pull.  The  forces 
on  the  front  wheels,  that  toward  the  right  due  to  the  unequal 
loading  of  the  drivers  and  that  toward  the  left  due  to  the 
oblique  direction  of  the  pull,  will  tend  to  balance  each  other. 
This  methocl  of  hitching  is  popularly  said  to  "divide  the  side- 
draft  between  tractor  and  plow." 


Fig.  43 

An  extreme  offset  hitch.    This  arrangement  is  sometimes  used  in 
orcharding  to  enable  working  closer  to  trees.    It  is  not  good  practice. 

If  the  relations  are  as  in  figure  43,  all  the  traction  load  will  be 
carried  by  the  right  driver.  This  arrangement  gives  bad  stresses  in 
the  tractor  frame  and  tends  strongly  to  slide  the  front  wheels  toward 
the  right.  With  this  hitch  to  a  medium  or  large  load,  it  would  be 
almost  if  not  quite  impossible  to  turn  to  the  left.     Some  tractors  are 


Bulletin  349]         A  study  of  sidedraft  and  tractor  hitches         145 

designed  to  do  such  work  well.  The  frame  may  be  made  extra  strong. 
The  steering  may  be  made  more  certain  by  deep  fins  on  the  front 
wheels  and  by  carrying  a  large  part  of  the  tractor's  weight  forward. 
The  friction  and  wear  in  the  bearings  due  to  side  forces  may  in  a  large 
measure  be  relieved  by  the  use  of  special  thrust  bearings  similar  to 
those  used  in  automobile  construction.  In  the  same  way  proper  design 
in  the  plow  intended  for  such  use  may  enable  it  to  do  good  work  even 
when  the  pull  on  it  is  at  a  considerable  angle  and  the  hitch  as  short  as 
may  be  necessary  for  such  work. 


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Fig.  43a 
(Courtesy  of  Monarch  Tractor  Co.) 

Rice  binder  mounted  directly  on  tractor. 

Mounting  the  implement  directly  on  the  tractor. — This  has  been 
attempted  with  more  or  less  success  by  a  number  of  manufacturing 
companies,  but  there  is  still  room  for  work  by  designers. 

Some  of  the  advantages  that  a  skilful  designer  might  secure  by 
direct  mounting  are : 

1.  Entire  avoidance  of  sidedraft. 

2.  Equal  forces  on  the  drivers. 

3.  Less  power  lost  in  overcoming  friction  of  supporting  wheels. 
•       4.  Easy  turning  in  smaller  space. 

5.  Saving  of  labor  cost  by  making  a  one-man  outfit  do  work  now 
requiring  two  or  three  men. 

Some  of  the  disadvantages  are : 

1.  The  time  and  labor  expense  of  mounting  and  dismounting 

the  implement  before  and  after  the  season's  use. 

2.  The  unavailability  of  the  tractor  for  many  other  uses  while 

the  implement  is  mounted  upon  it. 


146 


UNIVERSITY  OF  CALIFORNIA — EXPERIMENT  STATION 


3.  Difficulty  in  getting  through  gateways. 

4.  Increased  difficulty  of  getting  out  if  mired  down  or  stalled 

in  sand. 

Implements  drawn  by  two-wheel  tractors. — A  near  approach  to  a 
directly  mounted  tractor  plow  is  found  in  several  front-wheel-drive 
tractors  now  marketed  in  which  the  rear  of  the  tractor  is  borne  by  the 
plow  itself.  Sometimes  another  implement  takes  the  place  of  the 
plow  behind  one  of  these  tractors.  Cultivators,  disk  harrows,  mowers, 
and  seeders  have  been  used  in  this  way. 

Rotary  tillers. — One  or  more  American  manufacturing  companies 
are  experimenting  on  a  directly  mounted  rotary  tillage  machine  which 
gives  considerable  promise  of  efficiency  and  effectiveness.  A  small 
number  of  such  machines  have  recently  been  used  in  Wisconsin,  Texas, 


Fig.  44 

Implement  attached  to  two-wheel  tractor. 

to  direct  mounting  of  the  implement. 


A  near  approach 


and  California.  A  similar  machine  has  been  in  use  for  a  number  of 
years  in  Europe.  It  consists  of  what  is  in  effect  a  set  of  spring-tooth- 
harrow  teeth  mounted  on  a  rapidly  revolving  drum.  This  machine, 
by  its  chopping  action,  in  one  operation  reduces  the  soil  to  uniformly 
fine  pulverization  as  deep  as  required.  Thus  it  replaces  plow,  disk 
harrow  and  spike  tooth  harrow.  A  soil  free  from  large  stones  and 
other  obstructions  is  best  adapted  for  its  successful  use.  At  least  one 
European  type,  it  is  claimed,  climbs  out  of  the  ground  without  injury 
to  itself  when  it  reaches  a  large  rock.  Some  of  the  advantages  claimed 
for  these  machines  are : 

1.  More  thorough  and  uniform  pulverization. 

2.  More  efficient  use  of  the  power  of  the  motor. 

3.  No  compacting  of  the  subsoil. 

4.  Rendering  unnecessary  the  use  of  disk  harrow,  drag,  and  clod 

crusher  following  the  plow. 


BULLETIN  349]  A  STUDY  OF   SIDEDRAFT  AND   TRACTOR   HITCHES  147 

One  disadvantage  is  that  trash  such  as  cornstalks  is  not  well  turned 
under. 

Direct  mounting  of  binders  has  met  with  some  success  in  this 
country.  Figure  43a  shows  a  rice  binder  mounted  on  a  Monarch 
tractor  by  W.  J.  Shepard  of  Marysville,  California.  A  number  of 
these  were  used  during  the  last  three  seasons  in  the  rice  fields  of  the 
upper  Sacramento  Valley. 

The  Avery  Company  of  Peoria,  Illinois,  manufactures  a  special 
header  for  mounting  on  the  front  end  of  an  Avery  12-25  tractor. 

The  Caswell  Tractor  Grader,  figure  44a,  manufactured  by  Caswell 
Manufacturing  Company,  Cherokee,  Iowa,  is  a  direct  mounted  grader 


Fig.  44a 

(Courtesy  of  Caswell  Manufacturing  Co.,  Cherokee,   Iowa) 

A  direct  mounted  grader. 

which  loosens  the  soil,  elevates  it  to  a  box  holding  two  cubic  yards, 
hauls  to  the  desired  place,  and  dumps  or  spreads  as  desired. 

Special  tractor  hitches. — Chain  hitches  are  very  convenient  and 
satisfactory  for  many  purposes.  They  are  easy  to  apply  and  remove. 
Their  length  can  readly  be  adjusted.  They  show  definitely  the  direc- 
tion of  the  forces  upon  them  by  lining  up  with  those  forces.  Their 
flexibility  is  desirable  in  certain  cases.  They  have,  however,  certain 
disadvantages.  They  cannot  hold  a  wheeled  implement  on  a  down 
grade.  With  them  one  cannot  back  a  plow  to  clear  out  accumulated 
trash  unless  a  pole  is  supplied  in  addition.  They  are  not  so  stable  as 
a  rigid  hitch  would  be  when  the  plow  strikes  a  hard  spot. 

The  common  crossed  chain  hitch  is  often  used  and  has  the  valuable 
property  of  preventing  the  implement  from  "cutting  the  corners" 
when  the  tractor  turns.  The  pulls  in  the  two  chains  are  usually  not 
equal  and  may  vary  from  moment  to  moment  through  a  wide  range. 
This  is  true  when  it  is  used  for  plowing,  especially  when  turning  a 


148 


UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 


corner.  It  keeps  the  plow  in  the  ground  on  the  turns  better  than  a 
rigid,  hitch  and  enables  the  plowing  of  a  straighter  furrow  when  there 
are  slight  irregularities  in  the  steering  of  the  tractor.  It  does  not 
eliminate  sidedraft  and  unequal  loading  of  drivers  when  the  center 
lines  of  tractor  and  plow  are  offset. 

A  hitch  of  this  type  is  shown  in  use  in  figure  45  and  its  adjustment 
is  explained  in  figure  46. 

There  is  on  the  market  a  patented  chain  hitch  said  to  eliminate 
sidedraft.     It  consists  of  a  chain  passing  over  four  sheaves  which  are 

attached  two  to  a  bar  fastened  to  the 
tractor,  and  two  to  a  similar  bar 
carried  by  the  implement,  as  shown 
in  figure  47.  Its  characteristics  are 
much  the  same  as  those  of  the  common 
crossed  chain  hitch. 

A  hitch,  model  of  which  is  shown 
in  figure  47,  was  tested  in  1919  by 
L.  J.  Fletcher  and  the  writer  in  the 
presence  of  the  patentee  and  his 
engineer.  The  hitch  was  used  be- 
tween a  Cletrac  tractor  and  a  John 
Deere  three-bottom  tractor  moldboard 


Fig.  45 

Common  crossed  chain  hitch.  Prevents 
wagon  or  other  implement  from  cutting 
corners.  Enables  plows  to  stay  in  full  depth 
around  turns  and  to  go  straight  ahead  in 
spite  of  slightly  irregular  steering. 


plow  for  the  purposes  of  the  test.  The 
plows  stayed  in  the  soil  very  well  on  the 
turns.  That  sidedraft  was  present  was 
shown  by  the  fact  that  the  tractor  oper- 
ator had  to  hold  the  steering  wheel  to- 
ward the  unplowed  land  in  order  to  go 
straight  ahead. 

Fig.  46 

Model  of  common  crossed  chain  hitch. 
Chains  should  have  a  ring  at  one  end  and  a 
grab  link  or  a  grab  hook  at  the  other  for 
convenient  attachment  and  adjustment.  To 
cause  implement  to  move  over  to  right,  lengthen 
chain  at  x  or  shorten  at  y. 


BULLETIN  349]  A  STUDY   OF  SIDEDRAFT   AND   TRACTOR   HITCHES  149 


The  line  of  direction  of  the  combined  pull  of  all  the  chains  may 
be  found  readily  if  we  assume  the  pulls  in  the  chains  all  equal.  This 
assumption  is  very  nearly  correct  if  the  four  sheaves  have  little  friction 
on  their  shafts  and  are  not  pinned  to  prevent  their  turning.  In  figure 
48  draw  the  bisectors  of  the  angles  made  by  the  two  portions  of  chain 
running  from  each  sheave.  These  bisectors  will  meet  in  two  points, 
A  and  B.  The  line  AB  through  these  two  meeting  points  shows  the 
true  direction  of  the  tractor's  pull 
upon  the  plow  when  this  hitch  is 
used.  It  will  be  noted  also  that  the 
points  A  and  B  are  at  equal  dis- 
tances from  the  points  at  which  the 
sheaves  are  fastened  on  the  two 
attachment  bars.  Only  in  the  case 
where  the  line  AB  is  parallel  to  the 
direction  of  motion  of  the  tractor 
will  there  be  no  sidedraft.  If  the 
attachment  bar  is  not  symmetri- 
cally placed  on  the  tractor,  or 
rather  if  the  sheaves  are  not  sym- 


Fkf.  47 


A  patented  chain  hitch.  The  chain 
passes  around  four  sheaves,  two  of  which 
(those  on  the  tractor)  may  be  pinned  to 
prevent  their  turning.  This  hitch  does 
not  prevent  sidedraft. 


metrically  placed  with  re- 
spect to  the  center  line  of 
the  tractor,  so  that  the  line 
AB  does  not  pass  through 
the  midpoint  of  the  rear 
axle  of  the  tractor,   there 

Fig.  48 

Diagram  of  the  hitch  of  fig- 
ure 47.  The  line  AB  shows  the 
true  direction  of  the  pull.  There 
is  sidedraft  if  the  line  AB  is  not 
parallel  to  the  direction  of 
motion,  and  unequal  loading  of 
the  drivers  unless  the  line  BA 
produced  passes  through  the 
midpoint  of  the  rear  axle  of 
the  tractor, 


150 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 


will  be  unequal  loading  of  the  drivers.  Evidently  it  is  possible  with 
this  hitch  to  "divide  the  sidedraft  between  tractor  and  plow,"  as  with 
other  hitches  previously  explained. 

Hitches  to  adapt  horse  gang  plows  for  tractor  operation. — When 
the  tractor  makes  its  first  appearance  on  a  ranch,  there  are  usually  on 
hand  a  good  many  implements  in  fair  condition  designed  for  horse 
operation.  Often  at  a  small  expense  of  time,  labor,  and  materials  these 
may  be  adapted  for  tractor  operation  and  do  fairly  satisfactory  work. 
It  would  be  foolish,  however,  to  assume  that  these  adapted  implements 
could  generally  be  made  to  work  as  well  as  implements  especially 
designed  for  tractor  operation.     Since  plowing  requires  more  power 

than  any  other  farming  opera- 
tion, it  is  usually  the  particular 
job  for  which  the  first  tractor  is 
purchased.  Several  gang  plows 
designed  for  horses  may  be 
hooked  up  together  and  drawn 
by  rods  or  chains  from  one  heavy 
crossbar,  as  in  figures  49  or  50. 


Fig.  49 

Common  crossbar  plow  hitch  used 
for  adapting  horse  gangs  for  tractor 
operation. 

Each  gang  after  the  first  has  its  right  wheel  removed  and  the  axle 
hung  by  chains  or  clevises  and  rings  from  the  nearest  beam  of  the 
gang  next  ahead,  as  shown  in  figures  51  and  52.  This  arrangement 
enables  much  closer  placing  of  the  gangs ;  at  the  same  time  the  amount 
of  freedom  given  the  axle  enables  the  plows  to  make  the  turns  without 
"piling  up."  Figure  53  shows  a  similar  arrangement  designed  by  the 
Oliver  Chilled  Plow  Company  for  their  Bonanza  gang.  The  cast  iron 
spool  can  slide  lengthwise  of  the  axle  and  roll  backward  and  forward 
in  the  guide.  The  John  Deere  Plow  Company  manufactures  the 
device  shown  in  figure  54  for  use  with  their  New  Deal  gang  plows. 

When  the  several  gangs  are  hitched  to  an  ordinary  crossbar,  the 
chains  or  cables  drawing  the  rear  gangs  are  necessarily  longer  than 
those  for  the  front  gangs.  The  longer  hitch  to  the  rear  gangs  tends 
to  make  them  plow  deeper.  To  equalize  depth  of  plowing  the  hitch 
may  be  made  lower  on  the  rear  gangs.  Sometimes,  as  in  figure  55,  a 
piece  of  pipe  or  a  wooden  bar  carried  by  a  wheel  is  used  as  a  "lift"  to 
equalize  the  depth  of  plowing  and  also  to  prevent  fouling  of  the  chains- 
and  gangs  at  the  turns. 


Bulletin  349] 


A   STUDY   OF   SIDEDRAFT   AND   TRACTOR   HITCHES 


151 


Fig.  50 

Common   crossbar   plow   hitch.      Detail   showing   connection    to 
drawbar  swinging  between  horizontal  guides. 


Fig.  51 

Adapting  horse  gangs  for  tractor  operation.  Supporting  the 
right  axle  of  one  gang  by  ring  and  chain  from  a  beam  of  the 
next  forward  gang.  This  home-made  device  gives  the  necessary 
freedom  between  gangs  on  the  turns. 


Fig.  52 

Adapting  horse  gangs  for  tractor 
operation.  King  and  clevis  support 
for  the  axle  of  a  rearward  gang. 
Removing  the  wheel  brings  the  gangs 
closer  to  the  tractor  and  makes  oper- 
ation easier. 


Fig.  53 

Special  axle  support  designed  by 
the  Oliver  Chilled  Plow  Company  for 
their  Bonanza  gang  plow. 


152 


UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 


Fig.  54 
(Courtesy  of  the  John  Deere  Plow  Co.) 
Special  axle  support  designed  by  the  John  Deere  Plow  Co. 
for  their  New  Deal  gang  plows. 


Fig.  55 

"Lift"  for  the  longer  chains  when  several  gangs  are  attached 
to  a  common  crossbar.  The  wheel  and  pipe  prevent  the  rear  gangs 
from  plowing  too  deeply.  They  also  help  prevent  chains  and  gangs 
fouling  at  the  turns. 


The  Wilson  oblique  hitch,  figure  56,  pulls  evenly  on  all  the  gangs 
with  little  or  no  chance  of  fouling  on  the  turns.  A  larger  number  of 
gangs  can  be  used  than  with  the  common  crossbar,  because  the  gangs 
are  closer  to  the  tractor.  Also  a  narrower  headland  is  required.  Fig- 
ure 57  shows  this  hitch  in  use, 


Bulletin  349]         A  study  of  sidedraft  and  tractor  hitches         153 


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Fig.  56 

Wilson  oblique  plow  hitch.  Facilitates  turning  by  hitching  gangs 
closer  to  tractor.  All  gangs  are  same  distance  from  oblique  beam. 
Little  chance  for  fouling  on  the  turns.  Depth  of  plowing  is  about 
the  same  for  all  gangs.  Design  covered  by  U.  S.  patent  issued  to 
S.  Wilson,  Davis. 


Fig.  57 

Wilson  oblique  plow  hitch  in  use.    The  hitch  shown  here  has  also 
been  used  for  several  disk  plows  drawn  by  the  same  tractor. 


Pierce  harrow  cart. — In  dry-farming  operations  throughout  the 
interior  valleys  of  this  state  it  is  sometimes  necessary  to  use  harrows 
capable  of  covering  a  width  of  as  much  as  seventy  feet.  When  land  is 
free  from  large  gullies  a  harrow  cart,  if  well  designed  and  built,  is  a 
very  satisfactory  means  of  carrying  the  drawbars  needed  for  the 
numerous  sections.     In  1915  a  harrow  cart  was  designed  and  built  by 


154 


UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 


Fig.  58 

The  original  Pierce  harrow  cart  built  in  1915  by  George  W. 
Pierce,  of  Davis,  is  still  in  use.  Has  been  copied  by  grain  raisers 
throughout  the  interior  valleys  of  California. 


Fig.  59 

The  original  Pierce  harrow  cart.  Close-up  view  showing  some 
details  of  construction.  The  small  size  wheels  cut  into  the  soil, 
increasing  draft,  and  are  hard  to  lubricate. 


Fig.  60 

Cart  made  by  J.  C.  Luft  of  Davis.  The  original  Pierce  design 
is  followed  closely.  Slightly  larger  wheels  are  used  to  reduce  draft 
and  wear. 


BULLETIN   349]  A   STUDY   OF   SIDEDRAFT   AND   TRACTOR   HITCHES 


155 


George  W.  Pierce,  of  Davis.  The  original  is  still  in  use,  and  shown  in 
figures  58  and  59.  It  has  been  copied  by  many  ranchers  throughout 
the  Sacramento  and  San  Joaquin  valleys  and  is  being  manufactured 
commercially  by  J.  C.  Luft  of  Davis,  and  Milton  Carpenter  of  Dixon. 


Fig.  61 

Luft  cart  in  use  on  Sidney  Watkins  ranch.      Note  how,  even 
with  a  light  load,  the  small  wheels  cut  into  the  soil. 


Fig.  62 

Castor  wheel  made  by  M.  Carpenter,  Dixon.  The  swivel  wheels 
permit  hitching  tractor  to  an  end  of  a  boom  and  pulling  the  cart 
and  all  over  if  it  runs  foul  of  a  fence.  Because  of  their  small  size 
the  wheels  cut  in  badly,  making  draft  heavy  and  wear  rapid. 


The  Luft  make,  figures  60  and  61,  follows  closely  the  original  Pierce 
design  except  that  the  wheels  used  are  relatively  larger  making  for 
lighter  draft.    Several  sizes  may  be  had  to  order. 

Those  built  by  Carpenter,  figure  62,  have  castor  wheels  smaller 
relatively  than  those  of  the  original  Pierce.  The  swivel  mounting  of 
the  wheels  enables  attachment  of  the  tractor  to  the  end  of  a  boom  to 
pull  the  cart  clear  if  it  should  run  foul  of  a  fence  or  other  obstruction. 
If  this  is  attempted  with  a  cart  having  fixed  axles,  breakage  is  almost 
sure  to  result. 


156 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 


Figure  63  shows  the  "A  arrangement ' '  of  sections  used  with  a 
homemade  cart  built  by  the  Haussler  Brothers,  east  of  Davis.  It  has 
the  two  main  sets  of  harrow  sections  drawn  separately  and  at  a  con- 
siderable angle.  The  land  between  the  two  wings  is  harrowed  by  a 
section  attached  by  a  small  cable  to  the  top  of  the  mast.  This  arrange- 
ment gives  little  trouble  on  the  turns  and  in  the  gullies. 

The  cart  shown  in  figures  64  and  65  embodies  two  desirable  features 
not  found  in  the  other  carts  shown,  namely  large,  broad-tired  wheels, 
and  the  frame  hung  underneath  the  axle.    The  large  wheels  do  not  cut 


Fig.  63 

Home-made  cart  of  Haussler  Brothers.  The  "A"  arrangement 
of  the  sections  prevents  piling  up  at  the  turns.  The  middle  section 
is  drawn  by  a  small  cable  attached  to  the  top  of  the  mast.  Two 
sections  of  spring  tooth  harrow  attached  directly  under  the  cart, 
loosen  up  the  tractor  tracks. 


Pig.  64 

An  improved  harrow  cart.  The  large  wheels  decrease  draft  and 
bearing  wear.  The  underhung  frame  puts  the  boom  near  the 
ground,  enabling  a  more  nearly  level  pull.  This  means  better  work, 
less  draft,  and  less  trouble  at  the  gullies.  The  sections  may  be 
attached  to  the  boom  in  any  manner  desired. 


BULLETIN   349]  A  STUDY  OF  SIDEDRAFT  AND   TRACTOR   HITCHES 


157 


so  deeply  into  the  soil,  hence  require  less  draft.  Lubrication  and 
bearing-wear  troubles  also  are  greatly  reduced  because  of  the  slower 
turning.  The  low  boom  gives  less  trouble  when  one  end  is  over  a  gully 
and  permits  a  more  direct  pull. 

In  all  these  carts  the  intention  is  to  transport  from  field  to  field 
by  uncoupling  the  booms  which  butt  together  under  the  mast  and 
placing  them  on  the  cart,  then  piling  the  harrow  sections  on  top.  In 
some  cases  this  is  quite  a  job.  A  quick  and  easy  means  of  overcoming 
the  gate  bugbear  is  to  pull  the  cart  onto  a  low  sled,  release  the  open 


Fig.  64a 

Side  view  of  the  cart  of  figure  64.  Two  sections  of  spring  tooth 
harrow  dig  up  the  tractor  tracks.  Wheels  from  an  old  combined 
harvester  are  good  shape  and  size. 


Fig.  65 

An  underhung  frame,  large  wheel  harrow  cart  in  field  near 
Dixon.  The  attachment  of  the  long  booms  to  the  cart  frame  is  less 
convenient  than  the  form  shown  in  figures  64  and  64a. 


158  UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 

hooks  by  which  the  sections  are  held,  pile  the  sections  on  the  cart, 
attach  a  cable*  or  chain  to  the  sled,  and  slide  the  cart  lengthwise  of  the 
booms  through  the  gateway. 

Multiple  implement  hitches  are  often  desirable.  Usually  such  hitch- 
ing presents  little  difficulty.  Figure  66  shows  a  spike-tooth  harrow 
attached  by  a  chain  behind  a  disk  plow.  Pulverization  is  very  much 
better  and  moisture  is  conserved  if  the  dragging  is  done  at  once  after 
plowing.  The  hitch  shown  is  not  the  best  possible,  as  it  puts  all  the 
drag  load  on  the  right-hand  end  of  the  plow,  thus  increasing  the  wear 
on  the  plow  wheel  bearings.  A  better  arrangement  would  be  the  use 
of  a  narrower  drag  hitched  more  centrally  on  the  plow. 


Fig.  66 

Harrowing  while  the  clods  are  soft.  Much  better  pulverization 
is  secured,  especially  in  dryAveather,  if  the  drag  follows  the  plow 
immediately.     One  man's  time  is  saved  by  using  a  tandem  hitch. 

Figure  67  shows  a  tandem  hitch  including  a  double  disk  harrow,  a 
smoothing  harrow,  and  a  grain  drill.  This  makes  a  one-man  outfit  out 
of  implements  which,  if  used  separately,  would  require  three  men. 
One  difficulty  is  that  some  of  the  implements  may  get  less  attention 
than  they  require. 

For  drawing  two  or  more  grain  binders  by  the  same  tractor,  several 
hitches  are  on  the  market.  Figures  68  and  69  are  representative  types. 
(See  list  of  manufacturers  of  tractor  hitches,  page  163.) 

In  all  of  these  binder  hitches  some  sidedraft  is  certain  to  be  pro- 
duced by  the  oblique  pulls.  For  this  reason  it  is  well  to  make  sure 
that  the  bearings  of  all  carrying  wheels  are  in  good  condition,  clean, 
well  adjusted,  and  constantly  and  sufficiently  lubricated. 


Bulletin  349] 


A   STUDY   OF   SIDEDRAFT   AND   TRACTOR   HITCHES 


159 


Fig.  67 

(Courtesy  of  the  Emerson-Brantingham  Implement  Co.,  Rockford,  111.) 

Tandem  hitch  for  double  disk  harrow,  smoothing  harrow,  and 
grain  drill.  This  arrangement  saves  man  labor,  but  the  drill  may 
get  less  attention  than  it  needs. 


Fig.  68 
(Courtesy  of  the  Emerson-Brantingham  Implement  Co.,   Rockford,   111.) 
Binders  in  tandem.    Prompt  harvesting  often  means  getting  the 
grain    before    the    wind    threshes    it    out    for    the    crows    and    the 
sparrows.    An  operator  is  required  for  each  binder. 


Fig.  69 

(Courtesy  of  the  Meadows  Manufacturing  Co.,  Bloomington,  111.) 
Binder  hitch.     This  hitch  is  usable  between  binder  and  tractor 
or  between  first  and  second  binders.     It  prevents  the  binder  from 
"cutting  the  corners. ,J 


160  UNIVERSITY  OF   CALIFORNIA — -EXPERIMENT  STATION 


SUMMARY 

Sidedraft  is  no  mysterious  bugaboo.  It  is  subject  to  all  the  laws  of 
mechanics  that  apply  to  forces  in  general. 

Sidedraft  is  a  force  acting  sidewise  on  a  tractor  or  on  any  imple- 
ment. It  is  always  present  if  the  resisting  force  of  the  implement  pulls 
to  one  side  instead  of  parallel  to  the  direction  of  motion. 

No  hitch,  patented  or  otherwise,  can  prevent  sidedraft  when  the 
center  lines  of  pull  of  the  tractor  and  of  resistance  of  the  implement 
are  offset  and  the  hitch  is  to  the  center  of  a  symmetrically  placed  draw- 
bar. 

Test  for  sidedraft. — A  clevis  or  any  other  free  link  in  a  hitch  will 
set  itself  in  the  direction  of  the  force  it  is  transmitting.  If  that  direc- 
tion is  not  parallel  (in  the  horizontal  plane)  to  the  direction  of  motion, 
sidedraft  is  present. 

Effects  of  sidedraft. — Causes  poor  work,  makes  steering  hard,  in- 
creases wear,  repairs,  and  breakdowns,  and  makes  for  inefficiency  in 
general. 

Sidedraft  reduced. — It  may  be  reduced  by  making  the  total  pull 
required  and  the  offset  angle  as  small  as  possible.  Its  effects  may  be 
lessened  by  a  method  known  as  ' '  dividing  the  sidedraft  between  tractor 
and  plow."  It  is  possible  to  remove  all  sidedraft  from  tractor  and 
implement  by  offsetting  the  hitch  on  the  tractor  drawbar  so  that  the 
pull  will  be  straight  forward  from  the  implement;  out  when  this  is 
done  the  tractor  drivers  are  loaded  unequally,  which  may  produce 
effects  even  worse  than  sidedraft. 

Sidedraft  is  sometimes  unavoidable  and  sometimes  inexcusable. 

Down  draft  on  an  implement  due  to  poor  adjustment  may  cause 
nearly  as  much  trouble  as  sidedraft. 

How  a  plow  works. — Side  forces  and  vertical  forces  are  always  and 
necessarily  present  when  a  plow  is  in  use. 

Plow  adjustments. — Read,  ponder,  follow  the  directions  given  in 
the  handbook  furnished  with  the  machine. 

Drawbars  of  some  types  reduce  sidedraft  effects;  others  increase 
them. 

The  true  points  of  hitch  on  tractor  and  implement  determine  in  a 
large  measure  how  the  combination  will  act  when  in  use. 

Direct  mounting  of  tillage  and  harvesting  machines  upon  the  trac- 
tor has  large  possibilities,  in  that  sidedraft  may  be  eliminated  and  high 
efficiency  secured. 


BULLETIN   349]  A  STUDY   OF   SIDEDRAFT  AND   TRACTOR   HITCHES  161 

Homemade  hitches. — Many  good  hitches  for  special  purposes  have 
been  devised  by  farmers  and  others.  Descriptions  and  photographs  of 
some  of  these  are  given  in  this  bulletin. 

A  review  of  trade  publications  having  tractor  hitch  or  plowing 
information  gives  names  of  available  works,  their  contents,  and  where 
and  how  obtainable. 

A  list  of  manufacturers  of  tractor  hitches  is  given  on  page  163. 


BIBLIOGRAPHY 

The  Tractor  Field  Boole,  1921.  Pub.  by  Farm  Implement  News,  Masonic  Temple, 
Chicago,  111. 

Equalisers  and  Hitches  (1918),  by  E.  A.  White.  Pub.  in  "  Transactions, ' '  Am. 
Soc.  Agr.  Engrs.,  vol.  XII,  p.  124. 

Plow  Bottom  Design  (1918),  by  C.  A.  Bacon.  ''Transactions,"  Am.  Soc.  Agr. 
Engrs.,  vol.  XII,  p.  26. 

A  Study  of  the  Plow  Bottom  and  its  Action  on  the  Furrow  Slice  (1918),  by  E.  A. 
White.     ' '  Transactions, ' '  Am.  Soc.  Agr.  Engrs.,  vol.  XII,  p.  42. 

The  Botary  Tiller  or  Soil  Milling  Machine  (1914),  by  Max  Patitz.  *  'Trans- 
actions," Am.  Soc.  Agr.  Engrs.,  vol.  VIII,  p.  57. 

Tractor  Hitch  Merits  Serious  Consideration  (1918),  by  J.  E.  Schipper.  "Auto- 
motive Industries,"  June  27,  1918,  p.  1257. 

Tractor  Drawbar  Implements  and  their  Hitches,  by  F.  N.  G.  Kranich.  "Trans- 
actions," Soc.  Aut.  Engrs.,  1919,  Part  I,  p.  777. 

List  of  Principal  French,  German,  Italian,  and  Russian  Works  on  the  Plow. 
"Transactions,"  Am.  Soc.  Agr.  Engrs.,  vol.  XII,  p.  237. 

Coordinating  Theory  and  Practice  in  Tractor  Plow  Design  and  Operation,  Includ- 
ing the  Plow  Hitch,  by  A.  C.  Lindgren  and  O.  B.  Zimmerman  of  the  Experi- 
mental Department,  International  Harvester  Co.  "Agricultural  Engineering," 
Jan.,  1922,  Am.  Soc.  Agr.  Engrs.,  St.  Joseph,  Mich. 


TRADE    PUBLICATIONS    HAVING   PLOWING    OR    TRACTOR    HITCHING 

INFORMATION 

In  general,  hitches  designed  for  use  with  a  wheel-type  tractor  of  one  make  may 
be  used  readily  with  tractors  of  the  same  type  but  of  other  makes.  Likewise, 
equipment  designed  for  one  make  of  track-type  tractor  will  work  on  tractors  of 
the  same  type  but  of  different  makes.  But,  usually,  equipment  designed  for  track- 
type  does  not  work  well  with  wheel-type,  and  vice  versa. 

Advance  Rumely  Thresher  Co.,  17  Main  St.,  San  Francisco.      "Instructions  for 
Operating  the  12-20"  [or  other  size],  72  pages. 

Laying  out  fields  for  plowing.    Tractor  plowing  hitch.    Free,  in  limited  num- 
bers, to  owners  of  ' '  Oil  Pull ' '  tractors. 


162  UNIVERSITY  OF  CALIFORNIA — EXPERIMENT  STATION 

Avery  Co.  of  the  Pacific  Coast,  1401  Front  St.,  Sacramento,  Calif.     "Avery  Tractor 
Hitch  Book,"  48  pages. 

Laying  out  fields  for  plowing,  harrowing,  and  drilling.  General  for  hitching 
moldboard  plows.  General  for  hitching  disk  plows.  Hitches  for  2-  or  3 -disk 
plows.  Homemade  hitches  for  two  8-foot  or  10-foot  disk  harrows  or  drills 
(dimension  sketches).  Homemade  hitch  for  three  8-foot  disk  harrows  or  drills 
(dimension  sketches).  Hitch  for  Push  Header  and  Header  Barge.  Free  on 
request. 
C.  L.  Best  Gas  Traction  Co.,  San  Leandro,  Calif.  Blueprints  (dimension  drawings). 
S.  K.  5,  "Hitch  for  three  No.  31  Oliver  Plows."  (This  is  about  the  hitch 
shown  in  fig.  49.) 

S.  K.  6,  { '  Hitch  for  four  Gang  Plows  of  four  10-inch  bases  each. ' ' 
S.  K.  7,  "  Hitch  for  five  Oliver  Bonanza  Gang  Plows  to  a  C.  L.  Best  '  Track- 
layer. '  " 

S.  K.  78,  "Hitch  for  three  10-foot  double  disks  or  drills." 
S.  K.  79,  < '  Hitch  for  70  feet  of  harrows. ' ' 

S.  K.  80,  "Hitch  for  20  feet  of  Harrows  and  two  10-foot  drills." 
Sent  to  farmers  on  request. 
J.  I.  Case  Threshing  Machine  Co.,  Eacine,  Wis.     ' '  Plow  Manual, ' '  42  pages. 

Plow  hitches;    plow  adjustments;   laying  out  fields  for  plowing.     50  cents 
postpaid. 
Emerson-Brantingham  Implement  Co.,  Eockford,  111.     "E-B  Tractor  School  Text 
Book, ' '  40  pages. 

Hitches  for:  one  or  more  drills,  one  or  more  moldboard  plows,  one  or  more 
disk  ploAvs,  one  or  more  mowers,  one  manure  spreader,  combination  hitch  for 
disk  and  spike  tooth  harrows.     Free  on  request  ' '  while  they  last. ' ' 
Holt  Mfg.  Co.,  Stockton,  Calif.     ' '  Instruction  Book  for  Caterpillar  Disk  Plow, ' ' 
20*  pages. 

Hitch  for  two  or  three  disk  plows.     Free  to  farmers  on  request. 
International  Harvester  Co.,  201  Potrero  Ave.,  San  Francisco.     "Internal  Com- 
bustion Engines  and  Tractors,"  175  pages. 

Plow  adjustments,  care,  and  operation.     Free  on  request. 
Oliver  Chilled  Plow  Works,  San  Francisco.     ' '  The  Oliver  Plow  Book, ' '  200  pages. 
A  general  work  on  soils,  plows,  plowing,  adjustments,  hitching.     $1.00  post- 
paid. 
Twin  City  Company,  Minneapolis,  Minn.     "Instruction  Book  for  Twin  City  12-20 
Tractor,"  80  pages. 

General  work  on  tractor  management.  Hitch  for :  combination  of  plows  and 
peg  or  disk  harrows,  two  or  more  disk  harrows,  two  or  more  mowers,  two  hay 
loaders,  two  or  more  grain  drills.  Plan  of  a  general  utility  drawbar.  Free  on 
request.  (Give  size  of  tractor  if  not  12-20.) 
Vulcan  Plow  Co.,  Evansville,  Indiana.  "Service  Book,  Vulcan  Tractor  Plows, 
No.  41  Series,"  44  pages. 

Field  notes  on  plowing  (4  pages).     Free  on  request. 
Yuba  Products  Company,  433  California  St.,   San  Francisco.     "Instructions  for 
Operating  and  Adjusting  Yuba  Plows,"  24  pages. 

Hitches,  etc.,  for  one  or  two  Yuba  Disk  Plows.     Free  on  request. 


BULLETIN  349]  A  STUDY  OF   SIDEDRAFT  AND   TRACTOR   HITCHES  163 


MANUFACTUEERS  OF  TEACTOE  HITCHES 

The  Avery  Co.,  Peoria,  111.     1401  Front  St.,  Sacramento,  Calif. 

Combination  safety  release  and  automatic  coupler. 
Buller  Coupler  Co.,  Hillsboro,  Kansas. 

Automatic  coupler  for  tractors,  wagons,  and  automobiles.     Safety  release 
hitches. 
Milton  Carpenter,  Dixon,  Calif. 

Pierce  Harrow  Carts. 
Caswell  Manufacturing  Co.,  Cherokee,  Iowa.     Wm,  L.  Hughson  Co.,  Agents,  San 
Francisco. 

Hitches  for  all  makes  of  tractors  and  implements,  corn  binders,  one  or  more 
grain  binders,  one  or  more  dis\  harrows  or  grain  drills;   multiple  hitch  for 
various  implements;  adjustable  offset  plow  hitch. 
John  Deere  Plow  Co.,  Moline,  111.     San  Francisco. 

Hitches  for  grain  drills,  disk  harrows,  and  New  Deere  Gang  Plow. 
Dultmeier  Manufacturing  Co.,  Manning,  Iowa. 

Stub  poles  and  other  simple  tractor  hitches. 
Emerson-Brantingham  Implement  Co.,  Eockford,  111. 

Hitches  for  two  or  more  Osborne  binders,  any  size. 
Grand  Detour  Plow  Co.,  Dixon,  111. 

Lever  adjusting  plow  hitch  for  sidehill  work.     Safety  release  hitch. 
Hansmann  Manufacturing  Co.,  Long  Prairie,  Minn. 

Hitches  for  all  makes  of  tractors  and  implements.     Hitch  for  one  or  more 
binders.     Automatic  binder  hitch  truck.     Tractor  guide  (for  plowing).     Steer- 
ing poles  for  separators.     Steering  poles  for  graders.     Hitches  for  two  to  five 
grain  drills. 
International  Harvester  Co. 

Hitches  for  one  or  more  binders,  one  or  more  mowers,  corn  binder,  corn 
picker,  Deering  or  McCormick  push  harvesting  machine,  manure  spreaders  (stub 
tongue),  disk  harrows  (stub  tongue),  wagons,  grain  drills. 
La  Crosse  Plow  Co.,  La  Crosse,  Wis. 

Lever  hitch  for  adjusting  plowcut  in  side  hill  work. 
J.  C.  Luft,  Davis,  Calif. 

Pierce  Harrow  Carts. 
Meadows  Manufacturing  Co.,  Bloomington,  111. 

Hitches  for  tractors  and  binders  of  any  make.    For  one  or  more  binders. 
South  Bend  Chilled  Plow  Co.,  South  Bend,  Indiana. 

Safety  release  hitch. 
Towers  &  Sullivan  Manufacturing  Co.,  Eome,  Ga. 

Safety  release  hitch. 
Tractor  Appliance  Co.,  New  Holstein,  Wis. 

Outch  releasing  safety  hitches. 
Vulcan  Plow  Co.,  Evansville,  Indiana. 

Safety  release  hitch.     Lever  adjusting  plow  hitch  for  side  hill  work. 
Walter  A.  Wood  Mowing  and  Eeaping  Machine  Co.,  Hoosick  Falls,  N.  Y. 

Simple  tractor  hitches  for  various  implements. 


STATION  PUBLICATIONS  AVAILABLE  FOR  FREE  DISTRIBUTION 


No. 

253.  Irrigation  and  Soil  Conditions  in  the 
Sierra  Nevada  Foothills,  California. 

261.  Melaxuma    of    the    Walnut,    "Juglans 

regia." 

262.  Citrus   Diseases   of   Florida   and   Cuba 

Compared  with  those  of  California. 

263.  Size  Grades  for  Ripe  Olives. 

268.   Growing  and  Grafting  Olive  Seedlings. 

270.  A  Comparison  of  Annual  Cropping,  Bi- 
ennial Cropping,  and  Green  Manures 
on  the  Yield  of  Wheat. 

273.  Preliminary  Report  on  Kearney  Vine- 
yard Experimental  Drain. 

275.  The  Cultivation  of  Belladonna  in  Cali- 

fornia. 

276.  The    Pomegranate. 

278.  Grain   Sorghums. 

279.  Irrigation  of  Rice  in  California. 

280.  Irrigation  of  Alfalfa  in  the  Sacramento 

Valley. 
283.  The  Olive  Insects  of  California. 

285.  The  Milk  Goat  in  California. 

286.  Commercial    Fertilizers. 

287.  Vineerar  from  Waste  Fruits. 
294.   Bean    Culture   in    California. 

297.  The  Almond  in  California. 

298.  Seedless  Raisin  Grapes. 

299.  The  Use  of  Lumber  on  California  Farms. 
304.  A  study  on  the  Effects  of  Freezes  on 

Citrus   in   California. 

308.  I.  Fumigation  with  Liquid  Hydrocyanic 
Acid.  II.  Physical  and  Chemical  Prop- 
erties of  Liquid  Hydrocyanic  Acid. 

310.   Plum  Pollination. 

312.  Mariout  Barley. 

313.  Pruning  Young   Deciduous  Fruit  Trees. 

316.  The   Kaki   or   Oriental   Persimmon. 

317.  Selections  of   Stocks  in  Citrus   Propa- 

gation. 
319.   Caprifigs  and  Caprification. 


BULLETINS 

No. 
321. 
324. 


325. 


328. 
330. 
331. 
332. 
334. 

335. 

336. 

337. 
339. 

340. 

341. 

342. 
343. 
344. 

345. 

346. 
347. 

348. 
349. 

350. 
352. 

353. 
354. 
355. 


Commercial  Production  of  Grape  Syrup. 

Storage  of  Perishable  Fruit  at  Freezing 
Temperatures. 

Rice  Irrigation  Measurements  and  Ex- 
periments in  Sacramento  Valley, 
1914-1919. 

Prune  Growing  in  California. 

Dehydration  of  Fruits. 

Phylloxera-Resistant  Stocks. 

Walnut  Culture  in  California. 

Preliminary  Volume  Tables  for  Second- 
Growth  Redwoods. 

Cocoanut  Meal  as  a  Feed  for  Dairy 
Cows  and  Other  Livestock. 

The  Preparation  of  Nicotine  Dust  as 
an  Insecticide. 

Some  Factors  of  Dehydrater  Efficiency. 

The  Relative  Cost  of  Making  Logs  from 
Small    and    Large   Timber. 

Control  of  the  Pocket  Gopher  in  Cali- 
fornia. 

Studies  on  Irrigation  of  Citrus  Groves. 

Hog  Feeding  Experiments. 

Cheese  Pests  and  Their  Control. 

Cold  Storage  as  an  Aid  to  the  Market- 
ing of  Plums. 

Fertilizer  Experiments  with  Citrus 
Trees. 

Almond    Pollination. 

The  Control  of  Red  Spiders  in  Decidu- 
ous Orchards. 

Pruning  Young  Olive  Trees. 

A  Study  of  Sidedraft  and  Tractor 
Hitches. 

Agriculture  in  Cut-over  Redwood  Lands. 

Further  Experiments  in  Plum  Pollina- 
tion. 

Bovine  Infectious  Abortion. 

Results  of  Rice  Experiments  in  1922. 

The  Peach  Twig  Borer. 


CIRCULARS 

No.  No. 

70.  Observations    on    the    Status    of    Corn  172. 

Growing  in  California.  173. 
82.  The  Common  Ground  Squirrel  of  Cali- 

•  fornia.  174. 

87.  Alfalfa.  175. 

110.  Green  Manuring  in   California. 

111.  The  Use  of  Lime  and  Gypsum  on  Cali-  178. 

fornia  Soils.  179. 
113.  Correspondence  Courses  in  Agriculture. 

126.  Spraying  for  the  Grape  Leaf  Hopper.  181. 

127.  House  Fumigation. 

136.  Melilotus   indica    as    a    Green-Manure  182. 

Crop  for  California. 

144.   Oidium  or  Powdery  Mildew  of  the  Vine.  183. 

148.   "Lungworms."  184. 

151.  Feeding  and  Management  of  Hogs.  188. 

152.  Some  Observations  on  the  Bulk  Hand-  189. 

ling  of  Grain  in   California.  190. 

155.   Bovine  Tuberculosis.  193. 

157.   Control  of  the  Pear  Scab.  198. 

159.  Agriculture  in  the  Imperial  Valley.  199. 

160.  Lettuce  Growing  in  California.  201. 

161.  Potatoes  in   California.  202. 

164.  Small  Fruit  Culture  in   California. 

165.  Fundamentals    of    Sugar   Beet   Culture  203. 

under  California  Conditions.  205. 

166.  The  County  Farm  Bureau.  206. 

167.  Feeding  Stuffs  of  Minor  Importance.  208. 

169.  The   1918   Grain  Crop. 

170.  Fertilizing  California  Soils  for  the  1918  209. 

Crop.  210. 


Wheat  Culture. 

The    Construction    of    the    Wood-Hoop 

Silo. 
Farm   Drainage  Methods. 
Progress  Report  on  the  Marketing  and 

Distribution  of  Milk. 
The  Packing  of  Apples  in  California. 
Factors    of    Importance    in    Producing 

Milk  of  Low  Bacterial  Count. 
Control     of     the     California      Ground 

Squirrel. 
Extending  the  Area  of  Irrigated  Wheat 

in  California  for  1918. 
Infectious  Abortion  in  Cows. 
A  Flock  of  Sheep  on  the  Farm. 
Lambing   Sheds. 
Winter  Forage  Crops. 
Agriculture  Clubs   in   California. 
A  Study  of  Farm  Labor  in  California. 
Syrup  from   Sweet  Sorghum. 
Onion  Growing  in  California. 
Helpful  Hints  to  Hog  Raisers. 
County   Organizations   for   Rural   Fire 

Control. 
Peat  as  a  Manure  Substitute. 
Blackleg. 
Jack  Cheese. 
Summary  of  the  Annual  Reports  of  the 

Farm   Advisors  of  California. 
The  Function  of  the  Farm  Bureau. 
Suggestions  to  the  Settler  in  California. 


CIRCULARS — Continued 


No. 
212. 
214. 

215. 
217. 

218. 

219. 

224. 


225. 
228. 
230. 

232. 

233. 
234. 

235. 

236. 

237. 


No. 
Salvaging  Rain-Damaged  Prunes.  238. 

Seed  Treatment  for  the  Prevention  of  239. 

Cereal   Smuts. 
Feeding  Dairy  Cows  in  California.  240. 

Methods    for   Marketing   Vegetables   in 

California.  241. 

Advanced    Registry    Testing    of    Dairy 

Cows.  242. 

The  Present  Status  of  Alkali.  244. 

Control    of    the    Brown    Apricot    Scale  245. 

and  the  Italian  Pear  Scale  on  Decid-  246. 

uous  Fruit  Trees. 
Propagation  of  Vines.  247. 

Vineyard   Irrigation  in  Arid  Climates.  248. 

Testing  Milk,    Cream,    and    Skim   Milk 

for  Butterfat.  249. 

Harvesting    and    Handling    California  250. 

Cherries  for  Eastern  Shipment. 
Artificial  Incubation.  251. 

Winter  Injury  to  Young  Walnut  Trees 

during  1921-22. 
Soil  Analysis  and  Soil  and  Plant  Inter-  252. 

relations.  253. 

The  Common  Hawks  and  Owls  of  Cali-  254. 

fornia    from     the     Standpoint   of  the 

Rancher.  255. 

Directions  for  the  Tanning  and  Dress- 
ing of  Furs.  256. 


The  Apricot  in  California. 

Harvesting  and  Handling  Apricots  and 
Plums  for  Eastern  Shipment. 

Harvesting    and    Handling    Pears    for 
Eastern   Shipment. 

Harvesting  and  Handling  Peaches  for 
Eastern   Shipment. 

Poultry  Feeding. 

Central  Wire  Bracing  for  Fruit  Trees. 

Vine  Pruning  Systems. 

Desirable   Qualities  of  California  Bar- 
ley for  Export. 

Colonization  and  Rural  Development. 

Some  Common  Errors  in  Vine  Pruning 
and  Their  Remedies. 

Replacing  Missing  Vines. 

Measurement    of    Irrigation   Water    on 

the   Farm. 
Recommendations  Concerning  the  Com- 
mon     Diseases      and      Parasites      of 
Poultry    in    California. 

Supports  for  Vines. 

Vineyard   Plans. 

The  Use  of  Artificial  Light  to  Increase 
Winter  Egg  Production. 

Leguminous   Plants  as  Organic  Fertil- 
izer in  California  Agriculture. 

The  Control  of  Wild  Morning  Glory. 


